During World War II Malta managed to _____ most of Italian and German bombers by throwing up an effective anti-aircraft screen.

A．put out

B．shut out

C．come across

D．get across

在尿素水解器工艺操作指标不变的前提下，如果降低进料的尿素含量降低时，对提高尿素水解率（）。

A.有利

B.不利

C.无关

D.无法确定