流行性脑脊髓膜炎首选()
A.磺胺嘧啶
B.磺胺醋酰
C.环丙沙星
D.磺胺米隆
E.四环素
参考答案:A
解析:
磺胺嘧啶抗脑膜炎球菌作用强,常用作流行性脑脊髓膜炎首选药。
有一对夫妇第一胎生育了一个女孩,那么他们第二胎生育男孩的可能性为( )
A.1/4
B.1/2
C.1/6
D.1/8
I wrote a letter to John for his help during my high school years,without which I ________ the college entrance exam.
A.would fail
B.would have failed
C.should fail
D.must have failed