下列疾病可考虑行腺样体切除术的是：（）
A．分泌性中耳炎
B．慢性鼻窦炎
C．慢性中耳炎
D．腺样体肥大
E．变应性鼻炎
参考答案：A,B,C,D
The boy doesn't have _________ classes today.[ ]
A. any
B. a
C. some
D. much
If X and Y are independent events, which of the following must be TRUE（）
A. P( X or Y)=P(X)+P(Y).
B. X and Y cannot occur together.
C. P(X|Y)=P(X).
