临床疗效分析中随机分组常用的方法有()。
A.分层整群抽样
B.简单随机化
C.多阶段抽样
D.区组随机化
E.分层随机化
参考答案:B, D, E
I was born in Shanghai ______ we live in Beijing now. [ ]
A. so
B. and
C. after
D. but
用所给单词的适当形式填空。
1. What's he ___________ (do) now?
2. What ___________ (be) they going to ___________ (do) soon?
3. What ___________ (be) Tom ___________ (do)?
4. Can you sing? Yes, I ___________ (can).
5. Where ___________ (be) she going next month? She is ___________ (go) to Japan.