_______ of the students here _______ from the countryside.

A．Three-fourths; are

B．Three-fourth; is

C．Three-fourths; is

D．Three-fourth; are

有关痰液在各种肺部疾病中的表现哪项组合错误（）

A．慢性支气管炎咳白色泡沫痰

B．支气管扩张咳大量脓痰

C．肺炎球菌肺炎咳铁锈色痰

D．肺炎克雷白杆菌肺炎咳粉红色泡沫痰