题目

John as well as the other children who ____ no parents _____ good care of in the village. A.have, is being taken  B.have, has taken  C.has, is taken   D.has, have been taken 答案：A已知函数f(x)=x2，-2≤x≤02cosx，0＜x≤π.若方程f（x）=a有解，则实数a的取值范围是[-2，4][-2，4]．