What were you doing ?你那时正在做什么？
What were you doing ? A UFO came to that shop. What were you doing when the UFO came here. I was in front of the school library. I want to borrow some books from the school library. When I was walking back to classroom, I saw a UFO. The UFO landed on the street. And an alien got out of the UFO. The alien went to a shop. And it visited the Museum of Flight . then the alien went back to the UFO and took off.
Then the alien went back to the UFO and took off.
这是一篇扩写文章，能从课文的一方面入手，自己加以改进并丰富内容，值得鼓励！