—Do you think a radio is useful in learning English?

—Sure. A radio can _____ listening English songs and reports.

A．be used by

B．be used as

C． be used for

D．be used to

隐血试验的临床意义正确的是

A．肠结核阴性

B．消化道恶性肿瘤呈持续性阳性

C．克罗恩(Croh病常阴性

D．消化道溃疡持续性阳性

E．钩虫病常阴性