问题
选择题
---How long do you think it will be _____China becomes a developed country?
---At least 20 years, I guess.
A．that
B．until
C．when
D．before
答案
D.
it+段时间+before… 句型意为：要过多久才……。所在句意为：你认为中国要过多久才能成为一个发达国家。It …until…意为“直到……才……”与句意不合。