William led the others on their way across the plain. They passed hills and crossed bridges across the river. The road turned one corner after another, and the landscape around it changed again and again: one moment it was a forest soaring into the sky, the next it was a lively plain, and the next it was a winding river. Beside the dotted puddles, a few waterfowl rested, eyeing these aliens.

They finally found an area open enough for Rebecca to complete her last training session. Photon took off directly with her and quickly soared high into the sky.

"Our mission this time is very simple." Photon said to Rebecca as he flew, "The new thing is only to practice refueling in the air. Other than that, the rest of the time is for your revision."

"It's really great! Let's start now!" Rebecca replied eagerly.

Photon laughed, "That's surely OK. Now, control your speed until you don't exceed 500 km/h." Rebecca quickly adjusted her speed. Photon added, "Since it's not race time, we don't have a refueling plane, so I'll play its role." At this, both planes burst into laughter.

"In general, how long do the preparations take?" He asked.

Rebecca said the preparations included retracting the refueling pipes, docking and other procedures. According to the current state of technology, the total amount of extra time spent on a single air refueling was less than 10 seconds.

"It's already not easy." Photon sighed, "It's also a test of your tacit understanding with the refueling plane."

"You bet, but I'm an old hand. I can work perfectly with every new refueling plane within five practice sessions."

"You deserve to be called a former champion!" Photon cheered.

The two planes were perfectly stationary relative to each other. "How do the race rules dictate the amount of fuel left when refueling?" Photon asked. "Air refueling can be used when the fuel volume does not exceed 10% of the total tank capacity. Given the rules and technical limitations, it takes 1.5 minutes to fill up my tank." Replied Rebecca.

Photon thought carefully, then said, "Well, I suggest you go into hybrid mode as soon as you fill up and burn a little more fuel to make up for the mileage you've lost. I guess maybe your best performance isn't going to be shown with a full load of fuel."

"You are very experienced, Mr Photon. You must be a good fighter."

"Don't flatter me, Rebecca. Your performance is excellent. I believe you have mastered all the flying skills very well. Now let's go land first, and then you can show the others how good you are!"

"No problem!" The two planes landed slowly.

William approached them and asked about Rebecca's training. "She's mastering it very quickly." Photon answered confidently, "It's time for her to perform. I'll be right next to her all the time, and you can watch from the ground. You can pause at any time, Master, then we'll land immediately."

"Begin, then. Wait, you guys just said you were going to do a refueling show, but there are no refueling planes here. What's the best way to do this?" William was puzzled.

Everyone was at a loss for a moment. Suddenly, an idea flashed through Natalie's mind. "Got it! We can ask those butterfly robots to help us!"

Ranran suddenly realized, "Yeah, why didn't we think of them!"

"But are you sure they'll really be able to find a refueling plane?" William asked incredulously.

"Anyway, call them here first." Ranran found the heart-shaped logo the pretty girl sent, and pressed it. The butterfly robots quickly picked up the signal and within five minutes they were at their location.

After a brief conversation, butterfly robots understood the difficulties of William and his party. "Don't worry." Said one of the robots, "I think you know someone called Woodford."

"Of course. He even refitted Rebecca!" Ranran said.

"That's good. I thought you'd never heard of the name. He now has a refueling plane there who has participated in more than ten races and provided more than 3,000 refueling flights in total. He is very experienced. I think you can get in touch with Woodford and ask him to send the plane over. "

"OK! I'm going to contact him!" William darted to the backpack, pulled out his computer and sent Woodford an email.

Within minutes, he received a reply,

William,

I have received your email. I do have a refueling plane here. His name is Connor. But he needs to fill up his tank before he can go. You might have to wait a few more minutes, and I'll get him going as soon as I'm done.

Woodford

"Great!" William jumped wildly from the ground, "With Connor's help, the performance will be even more realistic! Thank you very much, dear butterfly robots. You are really very useful!"

"You're welcome. It's our duty. If you have nothing else to say, we will return to the castle."

"I have nothing else to say. Goodbye!" William said. The butterfly robots disappeared in sight.

For a few minutes, as she waited for Connor to arrive, Rebecca's emotions were overwhelming. "I'm about to have my first real performance!" She said excitedly to herself, "I must not let you guys down. I must show my strongest self!"

Finally, there was a roar of engine in the air. A huge shadow appeared over the heads of the party and slowly dropped until it came to rest on the ground covered with violets and lavender. William looked at Connor carefully. His fuselage was big, and his wings were thick, but that didn't mean he was slow. Instead, his maximum speed was even only about 50 km/h slower than Photon's. Unlike both planes, he was equipped with turbofan engines, which allowed him to fly faster with the same fuel economy and ensured that he had plenty of fuel left over for the other racing planes. Now he was looking kindly at the party and greeting them. William stepped forward and bowed. "Thanks for coming, Connor." He said, "Do you have enough fuel for Rebecca to refuel in the air?"

"Certainly no problem, Mr William." Connor replied firmly and confidently, "Can we start now?"

"Start!" At William's command, Photon and Rebecca quickly climbed to the heights. "When you get up, you can also watch Rebecca's maneuvers." William whispered to Connor. "I will." He answered.

Although the view was not as clear from the ground as it was from above, Connor was full of praise. "Rebecca learns so fast." He thought, "Woodford has told me her story. I might not be so surprised if it weren't."

They watched Rebecca perform one maneuver after another: top speed flight, horizontal and vertical maneuvers, fuel-efficient mode and hybrid mode. She did not overlook every maneuver, adjusting her posture with extreme precision for the best effect. Photon followed her. His face was impassive, but his heart was already filled with joy.

"It's your turn." Photon yelled at Connor as he lost altitude and sped past the party. So he started the engines and raced after Rebecca.

While waiting for Connor, Rebecca said to Photon, "Your timing was just right. I'm about to have less than 10% of fuel."

"Hee-hee, if I didn't keep an eye on your fuel remaining after every practice, you'd need to stop performing earlier."

This remark came as a surprise to Rebecca. She never knew that Photon had kept this parameter in mind. "He's so careful," She said, feeling a glow in her heart.

"I'm coming!" Connor's cheer rang through the air. Photon flew automatically to Rebecca's other side, making room for Connor. It was a masterstroke: the two planes quickly coordinated their speed, and Conner's refueling pipe quickly stuck to Rebecca's refueling port. "Ready to go at any time!" Connor said to Photon.

"Now!"

"Yes!" Blue-green algae kerosene poured into Rebecca's tank like surging waves. She felt a sudden surge of strength. As her fuel grew more, so did her energy. In the whole process, both of their speeds fluctuated by only 3%, almost in sync. After 90 seconds, refueling successfully completed. The refueling pipe slightly detached from the refueling port. Connor retracted it and returned to land, while Rebecca immediately went into hybrid mode. With the help of minitype fusion cell and motor, she quickly gained a speed advantage.

"Yay!" The cheers of all below clearly reached Photon.

"You are the lightning bolt on the field!" He told Rebecca. There was a smirk on her face. "My efforts have paid off." She thought triumphantly, "In the two years of my house arrest, I could not even imagine that I would soon be back to the same level as before."

The two planes returned to the earth, where they were greeted by thunderous applause and deafening cheers. "Congratulations, Rebecca." Ranran said, "You have successfully completed the training mission! Now, you can even race the next second!"

"Ha ha ha. You flattered me, Ms Ranran. I need to practice a few more times. Yet the fact that I was able to get back to where I was so quickly is even more than I expected. I knew in the past that I was powerful, but now I realize that I am more powerful than I thought. If I were still under house arrest, the result would be unthinkable. So I'm glad to meet you friendly alien friends. It is fate that makes me have to pick myself up. I will adjust my mind again and continue to write my legend. But I have said that in order to provide a great platform for more great competitors, this race will be the final one, so I should try my best and draw a happy full stop on the end of my career -- oh no, exclamation mark!"

"Great!" The cheers grew louder. Rebecca seemed to see a bright red airplane, with a huge gold trophy on her wings, smiling at her with satisfaction.