中毒性菌痢致病菌在我国较多见的是

A．志贺氏杆菌

B．福氏杆菌

C．宋氏杆菌

D．鲍氏杆菌

E．以上均不是

I insist that he _______ medicine instead of law.

A．has studied

B．studies

C．should study

D．studied