人体内常驻的条件致病菌成为致病菌而引起的感染称为
A．必然性感染
B．机会性感染
C．外源性感染
D．创伤性感染
E．偶发性感染
参考答案：B
根据句意和首字母提示完成单词
1. Han Hong is f______ as a singer.
2. —Who can s______ the problem?
—I believe everyone can.
3. During his l______, he invented many inventions.
4. The story happened last c
5. —Is there a______ else on the island?
—None.
羊水过多的常见病因是：
A．妊娠期糖尿病
B．胎盘增大
C．双胎输血综合征
D．母儿Rh血型不合
E．以上都是
