— Have you noticed some people _____ to check the exact signature before sending a text message?

— It happens. [ ]

A. bother

B. didn't bother

C. don't bother

D. are bother

锉刀按锉纹种类分，有（）

A.单齿纹锉、双齿纹锉

B.单齿纹锉、多齿纹锉

C.双齿轮纹锉、多齿纹锉

D.铣齿锉、剁齿锉