With so much work _________, they feel worried all the time.

A．doing

B．to do

C．done

D．having done

有关中心静脉的测压途径，临床上常用的不包括（）

A.右颈内静脉

B.锁骨下静脉

C.贵要静脉

D.颈外静脉

E.股静脉