There were fifteen for last week's talent show. [ ]
A. act
B. acted
C. acts
D. actor
答案:C
超声波探伤按探头的个数来分类,探伤的方法有三种:()、双探头法、多探头法。
在单位的日常工作中,既有“独唱”又有“大合唱”,你是如何看待的?