—My pet dog is missing and I am feeling so sad.

—Take it easy. Liu Ying and I will help you ______ it.[ ]

A. look out    

B. look after    

C. look at    

D. look for

选择电动机的额定电压等级要与电网电压（）。

A.高

B.低

C.高或低

D.相等