慢性弥漫性阻塞性肺气肿最主要的症状是（ ）
A．咳嗽
B．咳痰
C．逐渐加重的呼吸困难
D．心悸
E．咯血
参考答案：C
As one of the best-known American authors of 20th century, Ernest Hemingway wrote all the following novels EXCEPT （）.
A．For Whom the Bell Tolls
B．The Green Hills of Africa
C．The Sound and the Fury
D．The Old Man and the Sea
下列不属于客源特征的是( )。
A．指向性 B．多变性C．潜在性 D．时效性
