脑膜炎球菌致病的主要因素是（）。
A.外毒素
B.内毒素
C.荚膜
D.菌毛
E.自溶酶
参考答案：B
If it were not for the fact that I _____ very busy,I would go with you.[ ]
A. am
B. was
C. were
D. should be
血管检查方法与主要内容
