Tom, _____ play games here. Father is relaxing. [ ]
A. doesn't
B. can't
C. don't
答案:C
冬春风寒当令季节,预防感冒可服()
A.贯众、板蓝根、生甘草
B.贯众汤
C.藿佩汤
D.大青龙汤
E.桑菊饮
适用于联接用的螺纹是( )。
A.锯齿形螺纹
B.梯形螺纹
C.三角形螺纹
D.矩形螺纹