My pen friend and I keep in touch ________ sending e-mails often. [ ]

A. with      

B. by

C. on          

D. of

对肾自截的描述下列哪项不正确

A．肾内病灶无结核菌

B．全肾广泛钙化

C．膀胱结核好转

D．膀胱刺激症状基本消失

E．输尿管完全闭塞