囊肿的内容物可为（）
A.浆液
B.血液
C.半固体黏稠物
D.细胞成分
参考答案：A, B, C, D
用所给词的适当形式填空。
1. Li Hong is ___________ (make) a call.
2. Would you like ___________ (swim) with us?
3. My father ___________ (feel) happy.
4. Don't ___________ (hang) up the phone, please.
三个连续自然数之和是72，这三个数是______、______、______．
