单项选择题— Sorry, I have to ______ now. It's time for class. — OK, I'll call back later.
单项选择题It's impossible for a child to do so much work within a short period of time, ______
单项选择题—What do you think of the concert —I really enjoy it. I didn't expect it was ______ wonderful.
单项选择题—When was the first man with A(H1N1) flu in mainland China known for sure —______ May 11, 2009.
单项选择题One of the boys is ______, all the other boys are ______.