最先使用发射后不管穿甲弹的坦克炮的口径是多少（）
A.100毫米
B.105毫米
C.120毫米
D.125毫米
参考答案：C
The teacher didn't explain the problem clearly, so many students were _____. [ ]
A. confusing
B. mixing
C. confused
D. mixed
