炮眼长度大于（）米时，封泥长度不得小于1.0米。
A、2.0
B、2.5
C、3.0
参考答案：B
The little boy was so careless with his spelling that he often ________ letters from words.
A．left out
B．left behind
C．left off
D．let alone
为什么要盘车，如何进行，盘车的目的是什么？
