问题

The air in Lanzhou is getting much _____ now than a few years ago .
A:clean
B:cleaner
C:cleanest
D:the cleanest
B:cleaner
C:cleanest
D:the cleanest
正确答案是:
同类题型
I haven’t heard from him_____ last year. [ ]
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Which one did he choose from those watches? — He said he _______ the one made in Shanghai.
I don’t know when my son back, but when he back, I’ll call you.
He made another wonderful discovery, ______ of great importance to science.