烟雾信号是发烟的视觉信号,晚上、白天都可使用。()
参考答案:错
Scientists have advanced many theories about why human beings cry tears , none of () has been proved.
A. whom
B. which
C. what
D. that
膀胱刺激征为( )
A.尿频、血尿B.尿急、脓尿C.尿痛、排尿困难D.血尿、脓尿、尿频E.尿频、尿急、尿痛