As ________ clear from his manners, he seems to be much of a scholar.

A．being

B．is

C．if

D．though

架空送电线路的某铁塔位于高土壤电阻率地区，为了降低接地电阻，宜采取下列哪些措施？（）

A.采用接地模块

B.在接地沟内换填黏土（套黏土）

C.采用垂直接地体

D.加大接地体的直径