--Have you got the leaving time of the train for me?
---Yes, but you’d better of it by yourself.
A. make sure
B. be sure
C. to make sure
D. be certain
网友回答
(答案→)A. make sure
B. be sure
C. to make sure
D. be certain
解析：考查词组：A. make sure确保B. be sure和 be certain一定，有把握，had better后面接动词原形，句意：--你知道火车什么时候离开吗？--是的，你最好自己核实一下。选A。