Table tennis is easy to learn, and, by the same token , boys don''t need a lot of space to practice it.

A．by the same rule

B．symbolically

C．moreover

D．by logic

诊断尿路阳性结石的首选X线检查是

A．逆行肾盂造影

B．静脉尿路造影

C．肾动脉造影

D．腹部平片

E．肾周围充气造影