The children had only _______ slight temperature, but the doctor regarded the illness as serious enough for ________ hospital treatment.

A．a; 不填

B．不填; the

C．a; the

D．不填; a

在函数y=2x-5b中取不同的b值，可以得到不同的直线，那么这些直线必定[ ]

A.交于一个点

B.互相平行

C.有无数交点

D.不能确定