大家帮忙看一道英语题

题目

大家帮忙看一道英语题
Experts think we won’t have clean water to drink unless something ___soon,but much remains____ about environment protection.
A、would be done;doing B、is done;to be done
C、will be done;to do D、is done;to do
选哪个啊,记得给出解释 啊

答案

选B
第一空条件状语从句,
第二空remainto be done 固定搭配
to do 表示要去做,而且是被完成 ,所以是to be done