演示文稿it的用法.ppt

“it”的用法? “it”一词在英语中应用广泛，形式多样，充分了解其相关结构和用法，会对我们的英语学习很有帮助。 1. it用作人称代词 it用作人称代词，不仅可以指事物，也可指人。它的主要功能是指代。为避免重复，可用它来代替词、词组或整个句子。 ①—Have you seen my dictionary? ?? —Yes, it is on my desk. ②—Who is there? —It is me. 2. it用作非人称代词 it用作非人称代词，其作主语时通常没有具体意义，用于表示气候、天气、温度、时间、地点、距离和环境等意义的句子中。 ① It is ten miles from here. ② It is too noisy for me to study here. 指代时间的it还可以用在It is...since...句型中。 It is ten years since we got to know each other. 3. it用作先行代词 it作先行代词的用法是充当形式主语或形式宾语，后面的真正主语或真正宾语通常是不定式结构、动名词或名词性从句。 1) 代替不定式，被替代的成分要置于句末。 ①It is of great help to master a foreign language. ②It took me a week to rewrite the paper. ③I consider it advisable to tell her beforehand. ④I find it quite necessary to make some changes. 2) 作先行代词，代替动名词。 it代替动名词，主要用于下面的结构中。注意，这种结构中不宜用不定式。 It is no good (no use, useless, senseless, dangerous, enjoyable, worthwhile) + 动名词 It is a waste (a nuisance, hard work) + 动名词 ①It is worthwhile making another try. ②It’s dangerous sleeping out in the woods at night. ③It is hard work persuading him into doing it. ④I find it a waste spending so much money drinking and eating. 3) 作先行代词，代替名词性从句。 该结构中的名词性从句可用that, what, when等引导。 ①It is obvious that metals in common use are very important in our life. ②It happened that she was not at home when I called. ③ It is not known what caused the accident. ④Has it been found out who is the murderer? ⑤We have made it clear that she has nothing to do with the case. ⑥It is a mystery when they got married. 4. it用于强调结构中 1) It is + 被强调部分 + that... 该句型中，将被强调部分放在that前，其它部分置于that之后。被强调部分可以是主语、宾语、表语或状语。如果去掉“It is...that...”结构，句意仍然完整。 ???? It is from the sun that we get light and heat. 2) It is not until + 被强调部分 + that... 该句型主要用于强调时间状语，译作“直到……才……”。 It was not until she took off her dark glasses that I realized she was a famous film star. = Not until she took off her dark glasses did I realize she was a famous film star. = I didn’t realize she was a famous film star until she took off her dark glasses. 5. it的习惯用法 it的习惯用法较多地出现在口语或非正式文体中，这时it已失