Only then______ have a chance _____ an astronaut.
–Is Tony home? -Yeah, he’s just _______ back from Chengdu.
Sam is a very good man. He always tries __________ best to help others.
We will have a big test ___________ June 12th. Good luck to you.
Who is ___________ man under the tree?
They have no classes ________ Saturday and Sunday. A. in B. on C. at D:from