抽芯铆钉是由什么和什么组成？
参考答案：
是由空心铆钉和芯棒组成。
Peter is busy _ _ at school, but he never forgets _ __ exercise every day.
A. working; doing B. working; to do C. at work; doing
However hard I tried, I just couldn't ________them of the truth of my story. [ ]
A．remind
B．convince
C．rid
D．inform
