Living in the country，Peter doesn’t  write often，but we do hear from him________.

A．now and then

B．sooner or later

C．at the same time

D．more or less

当结构尺寸和工作油压既定时，十字头式转舵机构所能产生的转舵扭矩将随舵角增加而（）.

A.增加

B.减小

C.不变

D.先减后增