引起肺源性心脏病的支气管、肺疾病中最常见的病因是（）
A.支气管哮喘
B.慢性阻塞性肺疾病
C.重症肺结核
D.支气管扩张
E.结节病
参考答案：B
围堰使用期间河流的常水位为+2.0m，可能出现的最高水位（包括浪高）为+3.0m，则该围堰项的最低标高应为（）。
A.+2.5m
B.+3.0m
C.+3.5m
D.+4.0m
A number of students _____ the sports meeting. The number of the students who take part in ____200.[ ]
A. take part in, is
B. takes part in, are
C. taking part in , are
D. taking part in, is
