________ seems to be a strong competition in China for senior high students to enter college or university.
A programmer may make mistakes in a wrong analysis of the situation _____ the programme was based.
__________ the directions exactly, you will never get confused.
Some people have called ________ the worst period ever for Pop Music.
Only after he had spent several nights working on the math problem _______ to wonder whether the problem was wrongly set.
__________ David could remember, he had never said an angry word to that customer.