The boy went in _______ when he left for school that he left his key inside the house.
The theory by Einstein was later to prove true, but at that time few people could accept it.
____________ your father saw you, what would he say? A. IfB. Suppose C. Unless
I'm happy ________________ you are happy. A. if B. unless C. as long as
_________ I am, I will be thinking of you. A. Where B. Wherever C. Who
Wuhan lies _____ the Changjiang River and the Han River meets. A. where B. wherever C. that