介词
1. It’s bad manners to laugh ______ others when they are in trouble.
A. at B. to C. in D. at
2. Li Lei goes to school _____ 7:10 in the morning.
A. on B. for C. in D. at
3. ---- When did you leave home this morning?
---- _____ half past seven.
A. On B. To C. In D. At
4. ---- Mary won first prize in the speed contest.
---- No wonder. She began to learn English _____ the age of four.
A. from B. in C. on D. at
