题目

I have two children, and ________ of them are working in the west of China.A．allB．bothC．neitherD．either 答案：B解析:两个孩子应该考虑both/neither/either，后面动词是are所以用both当x=3时，下列各式中值为零的分式是（　　）A．x-3x2-6x+9B．2x-3C．3x-9x2+9D．3-x2x-6