We used to see each other _____, but haven’t heard from him since last year.
He didn’t explain _______ why he was late, which made us unhappy.
Don’t spoil (惯坏) the child. Can’t you make your little son ______ himself?
It is well known that Madam Curie won two Nobel Prizes for her scientific ______.
—Would you like to watch the basketball match with me this evening? —______. I like basketball very much.
Missing the train means _____ for another two hours.