从句中不担任成分，有时可省略。
2．考查名词性从句的语序和时态。
3．考查it作形式主语、形式宾语的情况。如：
(1)It＋be＋形容词(necessary, important, obvious等)＋that从句．
(2)It＋be＋过去分词＋that从句．
(3)It＋be＋名词(a surprise, a fact, a shame, an honour等)＋that从句．
(4)It＋不及物动词(appear, happen等)＋that从句．
4．名词性从句中的虚拟语气。如：
(1)It is (was)＋ essential (important, natural…) ＋that…；
(2)It is (was) suggested (demanded, wished, desired…)that…等。
5．what引导名词性从句时的语义功能和语法功能。如：what＝the thing that/anythin g that…； what
