So far we have done a lot to build a low-carbon economy, but it is ____ ideal (理想). We have to work still harder. 

—You don’t seem to be quite yourself today. What’s wrong? —Oh, I’m suffering from a cold. Nothing serious,  _____. 

He said he would come . He didn't _______.

--Students should devote most of their time to studying rather than playing computer games.  ---________. No pains, no gains.

Expensive restaurants are not_________ the best.