動(dòng)詞不定式是由“不定式符號(hào)to+動(dòng)詞原形”構(gòu)成的一種非謂語(yǔ)動(dòng)詞結(jié)構(gòu)。有些動(dòng)詞不定式不帶to，動(dòng)詞不定式可以作句子的主語(yǔ)、表語(yǔ)、賓語(yǔ)、定語(yǔ)、補(bǔ)語(yǔ)、狀語(yǔ)或單獨(dú)使用。不定式保留動(dòng)詞的某些特性，可以有自己的賓語(yǔ)、狀語(yǔ)等。動(dòng)詞不定式和它后面的賓語(yǔ)、狀語(yǔ)等一起構(gòu)成短語(yǔ)，叫作不定式短語(yǔ)?，F(xiàn)對(duì)九年級(jí)動(dòng)詞不定式的用法作一次簡(jiǎn)要梳理。
一、用作主語(yǔ)
直接把動(dòng)詞不定式置于句首的情況不多，多數(shù)情況用it作形式主語(yǔ)，把真正的主語(yǔ)——?jiǎng)釉~不定式置于句末，特別是不定式短語(yǔ)較長(zhǎng)時(shí)。動(dòng)詞不定式作主語(yǔ)，謂語(yǔ)動(dòng)詞用第三人稱單數(shù)形式。帶疑問詞的不定式短語(yǔ)作主語(yǔ)常置于句首，復(fù)合不定式結(jié)構(gòu)作主語(yǔ)常置于句末。如：
1. As young adults, it is our duty to try our best to deal with each challenge...
2. The head teacher said it was necessary to talk with his mother.
3. How to make requests politely is important.
二、用作表語(yǔ)
動(dòng)詞不定式作表語(yǔ)，常說明主語(yǔ)的內(nèi)容、性質(zhì)、特征。如：
1. The best way to improve your English is to join an English club.
2. The first thing is to greet the teacher.
一、用作主語(yǔ)
直接把動(dòng)詞不定式置于句首的情況不多，多數(shù)情況用it作形式主語(yǔ)，把真正的主語(yǔ)——?jiǎng)釉~不定式置于句末，特別是不定式短語(yǔ)較長(zhǎng)時(shí)。動(dòng)詞不定式作主語(yǔ)，謂語(yǔ)動(dòng)詞用第三人稱單數(shù)形式。帶疑問詞的不定式短語(yǔ)作主語(yǔ)常置于句首，復(fù)合不定式結(jié)構(gòu)作主語(yǔ)常置于句末。如：
1. As young adults, it is our duty to try our best to deal with each challenge...
2. The head teacher said it was necessary to talk with his mother.
3. How to make requests politely is important.
二、用作表語(yǔ)
動(dòng)詞不定式作表語(yǔ)，常說明主語(yǔ)的內(nèi)容、性質(zhì)、特征。如：
1. The best way to improve your English is to join an English club.
2. The first thing is to greet the teacher.