49. You must go there at once because the situation       prompt action.

A．calls for

B．calls back

C．calls at

D．calls on

接触流行性腮腺炎儿童后，应（）

A.立即检疫3周

B.不须检疫

C.可用丙种球蛋白预防

D.立即接种腮腺炎减毒活疫苗

E.检疫至腮腺肿大