It is vital/ necessary/ important/ urgent/ imperative/ desirable/ advisable/ natural/ essential+that+动词原形
It is time/abouttime/hightime+that+一般过去时
proposal/suggestion+that+动词原形
lest+that+should+动词原形
if only+that+would+动词原形
2)状语从句的考点为:
非if引导的条件状语从句,此类句子多用at times,provided,so long as,in case,once等来替代if由even if/so,now that,for all等引导的让步状语从句,just/hardly…when引导的时间状语从句;more than, as…as,not so much as,the same as,as much as等引导的比较状语从句