有些传染病起病急骤，但临床表现并不明显的时期是
A．前驱期
B．潜伏期
C．症状明显期
D．平稳期
E．恢复期
参考答案：A
下列几种“影”，分别属于哪种光学现象？影子：______；电影：______；倒影：______．
用所给动词的适当形式填空。
1. Daniel, ___________(not talk) in class.
2. My brother______ (be) born in 1990 in Qidong.
3. Tom, with his classmates, often _______ (fly) kites in the open air.
4. Listen! How nice the music ______ (sound)!
5. Be quiet, the babies _______ (sleep) next door.
