The little boy was so careless with his spelling that she often_____ letters from words.

A．left out

B．left behind

C．left off

D．let alone

安全监督检查人员依法可以行使()职权。

A.要求被检查单位购买其指定的产品

B.收取验收费

C.现场处理权

D.紧急避险权