Is this the reason _____ in the report for her success in the job ?

A．she explained

B．what she explained

C．how she explained

D．why she explained

矫直棒料时，为消除因弹性变形所产生的回翘可()一些。

A、适当少压 

B、用力小 

C、用力大 

D、使其反向弯曲塑性变形