it 与名词性从句

it作形式宾语、形式主语 it 作形式宾语一定义 当不定式（短语），动名词（短语）或从句在句子中作宾语时，为保持平衡，避免句式结构的混乱，常用it 作形式宾语，而将真正的宾语方在句尾。此时it只起引导作用，无意义。adj.n.(for sb) to do sth.从句doing sth2 结构+S + v + it+句型结构为“1236”1指形式宾语it；2指宾语的两种形式：形容词和名词；3指真正的宾语的三种形式：不定式短语，动名词短语或从句6指主句中常用动词：think, believe, consider, make, find, feel. find possible1.S+ think + it+ necessary +( for sb. ) to do sth. /clause. feel important a rule2. S+ V + it + ones duty + ( for sb. ) to do sth. /clause an honour no good3.S + V + it + + doing sth. no use 三用法当不定式、动名词、从句等用作宾语且其后跟有宾语补足语时，就应在宾语补足语前使用没有具体意义的形式宾语，而将真正的宾语移至句末。it作形式宾语,代替不定式、动词ing短语、从句.其基本结构为“动词+it+宾语补足语+不定式(动名词或从句)”：4 例句it作形式宾语,代替不定式、动词ing短语、从句.1.He found it difficult to stop smoking 2.I think it best that you should do more exercise.3.She thought it no good worrying about him。4. We find it necessary that we practise English daily.5. She made it a duty that she takes care of her sick mother.6. I have made it my habit that I get up before 6:30 everyday .5 巩固练习（1） They found it difficult（发觉难）to finish their work in two days. （2） We think it our duty（认为是我们的职责) to clean our classroom every day. （3） I dont think it possible to master a foreign language without much memory work. (4) 他认为从现在开始努力学习赶上他人是有可能的. He thinks it possible that he works hard to catch up with others.（5）他发现很难使别人理解他. He found it difficult to make himself understood. 我认为我们保持冷静很重要. I think it important that we should keep calm.6 it 作形式宾语的特殊用法（1）某些表示“喜、怒、哀、乐”的动词，如like, enjoy, love, hate, dislike, appreciate等 后往往不能直接接宾语从句；必须先由it担任形式宾语，指代后面从句所述内容,再接从句(通常是if/when引导).1.We would much appreciate it if you could do us that favour.要是你们能帮我们这个忙，我们将非常感激。2.Id prefer it if I didnt have to finish the work.要是我不必完成那项工作，那就太好了。3. I would appreciate it if you would turn the music down .4. I hate it when people talk with their mouths full. （2） 某些含有介词的动词短语如 depend on, rely on，answer for, insist on,stick to，look to（注意，指望，照看），count on（指望，依靠），see to（负责，注意，照料）,等结构中往往不能直接接宾语从句；必须先由it担任形式宾语,再接从句. 1.Ill see to it that everything is ready in time. 我将负责按时做好一切准备。 2.You may depend on it that Tom will help you with your English.(你放心，汤姆会帮助你学英语的。) You may depend on it that theyll support you. 3.Im counting on it that you w