艾滋病最常见的机会性中枢神经系统感染是（）
A.脑囊虫病
B.脑弓形体病
C.单纯疱疹病毒性脑炎
D.化脓性脑膜炎
E.新型隐球菌脑膜炎
参考答案：B
用所给动词的适当形式填空。
1. We were looking forward to____ (visit) Shanghai World Expo .
2. The law of gravity____ (discover) by Isaac Newton about 350 years ago.
3. You must try your best to stop him____ (make) the same mistake again.
4. Jack said he____ (return) the two books to the library in a week.
5. He prefers____ (take) part in the public activities rather than stay at home alone.
亚慢性毒性试验的设计中，哪个剂量组相当于观察到LOCAL（）。
A.高剂量组
B.中剂量组
C.低剂量组
D.最低剂量组
E.对照组
