问题 选择题

When you are _______ about which button to press on the complicated machine, you can either read the user's guide for guidance or fax us for specific instruction. Don't ______ the trial-and-error method.     [ ]

A. insure; do  

B. ensure; make    

C. uncertain; try    

D. unsure; touch

答案

答案:C

单项选择题
单项选择题