It is +段时间＋since+主语＋did. 自从……到现在已经多长时间了
It is a pity/ a shame…that clause. 真遗憾
It is important for sb.to do.… 做……很重要
It is important that clause. ……是很重要的
It is kind of sb. to do 你真好，谢谢你
It is no good doing 做……是没有用的，做……没有好处
It is no use doing 做……没用的
It is suggested / ordered/ commanded /…that +clause. 有人建议
It is the first/second/third time that 这是我第一次/第二次做……
It is time (for sb.) to do 是……做……的时候了
