entists can exactly figure out what ________ happened ________ at that time, which caused the extinction of the dinosaurs.

As we all know, ________ earth moves around ________ sun.

He _____ English for ten years by the time he takes the examination

Hainan is a very large island and it’s the second island in China.

I plan to go to a movie. Would you like to go with me— ___________ . That’s my favorite.