All the workers are working hard to create _____ we hope will be the best means of transport in the 21^st century.

A．what

B．where

C．which

D．that

体外冲击波碎石可能的并发症有（）。

A.血尿

B.肾绞痛

C.梗阻

D.感染

E.尿潴留