—Why do you want to learn French?  

—I think it is fun _____ language after English.   [ ]

A. to learn a

B. learn a

C. to learn another

D. learning another

对负载率很低即正常使用时低于( )，而且损失率又很高，通过计算证明是“大马拉小车”的变压器，应予以调整或更换。

A．60%

B．70%

C．30%

D．50%