By the time he was 38, he had become ________ principal of ________ university.
He doesn’t like the man, so he will not ______ him to be the president.
Coal was formed out of dead forests by chemical ______ .
He is trying hard to feed and ____ his family.
They say that ____Chinese language is particularly difficult for ____ European.
It remains ______ whether he will pass the exam this time.