With all his attention ________ on his experiment, he has no time to spend with his family.[ ]

A．paid  

B．focused

C．attracted  

D．settled

不能引起特异性感染的是（）

A.破伤风杆菌

B.结核杆菌

C.绿脓杆菌

D.真菌

E.梭状芽孢杆菌