— What about the student in your class, Mr. Wang?

— The doctor said that          sleep caused him poor memory and poor concentration.[       ]

A. lacking of  

B. lacked in    

C. lacking    

D. lack for

槽孔型混凝土墙施工依槽孔的成槽方法有( )。

A．射水法

B．抓斗开挖槽孔

C．冲击钻或回转造槽孔

D．深层搅拌桩成墙

E．锯槽法