There are two________ in the basket. [ ]
A. potatos
B. potatoes
C. potato
D. zoos
答案:B
已知4x2-4x+1=0,则2x=______.
利福平抗结核作用的特点是
A.选择性高B.穿透力强C.抗药性缓慢D.在炎症时也不能透过血脑屏障E.对麻风杆菌无效