不定式(to do)
　　动词不定式的构成与特征 　　动词不定式是动词的一种非限定形式，由"to+动词原形”构成，在句中起名词、形容词或副词的作用，同时也保留动词的一些特征，可以带宾语或状语，如下: 　　动词不定式:to do相当于①名词(可作主语)；②形容词(可作定语)；③副词(可作状语)。 　　否定式:not+to do动词不定式的功能:
　　雅思写作中动词不定式常作:主语、宾语、表语、定语、状语和宾语补足语。
　　不定式作主语
　　To do this is to cut the foot to fit the shoe. 　　这样做是削足适履。(雅思写作中用来反驳别人观点的杀手锏!)

To subsidize artists and musicians is a wise measure to preserve the traditional culture. 　　资助艺术家和音乐家是保护传统文化的明智措施。( “to subsidize artists andmusicians”在句子中作主语，同时“to preserve the traditional culture”作前面的名词短语“a wise measure”的定语。主语和定语均用不定式，其一，语气强烈;其二，显得很有文采。记住这个句型，在适当的时候运用“乾坤大挪移法”!)

不定式作主语时，往往由“it”代替它作形式主语，不定式则移至谓语之后。
　　It is no exaggeration to say that friendship is to people what perfume is to flowers. 　　可以毫不夸张地说，友谊对于人正如同芬芳对于花儿。(“it”作形式主语，划线部分为动词不定式短语作真正的主语。)

学生常犯错误如下: 　　That is very difficult to find a satisfactory job without a diploma nowadays.(误)
It is very difficult to find a satisfactory job without a diploma nowadays.(正)
现如今，在没有文凭的情况下，要找到一个满意的工作困难重重。
　　不定式作宾语
　　As for those college students from economically humble background，governmental assistance could help to ease the financial burden of rising education costs. 　　对于贫困大学生，政府的援助可以缓解上涨的学费压力。
　　I believe it best to leave the matter entirely to children's discretion. 　　我认为把这件事情完全交给孩子自行决定是比较好的做法。(“it”为形式宾语，“best”为宾语补足语，“to leave the matter entirely to children's discretion”是真正的宾语。)不定式作表语。
　　The next step is to ensure that all the children in developing countries canhave free access to compulsory education. 　　下一步要确保发展中国家所有的孩子能接受义务教育。
　　The first countermove is to lay down more rigid laws and regulations to deterthe would be criminals. 　　第一个对策是制定更多严格的法律法规来阻止潜在的犯罪分子。
　　What we should do is to absorb the essence and discard the dregs. 　　我们要做的是取其精粹，去其糟粕。
　　不定式作定语
　　The government should organise some large-scale campaigns to arousepeople's awareness of environmental protection. 　　政府应组织一些大规模的活动来唤醒人们的环保意识。
　　Nowadays, with the wide application of computers, many adults feel thepressing need to acquire commuter literacy. 　　现如今，随着电脑的广泛应用，许多成年人感到学习电脑知识的迫切需要。
　　The Internet is a convenient way to convey information. 　　互联网作为传播信息的方式很方便。
　　不定式作目的状语
　　To associate/mingle with friends, we should be honest and open. 　　为了结交朋友，我们应当诚实并且开朗。
　　Our government should take stronger and harsher measures to combat thelittering behaviour. 　　我们的政府应当采取更强有力的措施来防止乱丢垃圾的行为。
　　不定式作宾语补足语
　　The 21st century requires us to be equipped with advanced knowledge. 　　21世纪要求我们用先进的知识武装自己。
　　The fierce social competition makes people work and live under greatpressure. 　　激烈的社会竞争迫使人们生活和工作在巨大的压力之下。(此句型为:“make sth.”，即省略“to”的动词不定式。)
　　Advanced intelligent machines such as robots enable people to work moreefficiently and comfortably. 　　先进的智能机器如机器人能使人们工作得更加高效和舒适。
　　学生常犯错误如下:
　　He hoped his sister to lend him a hand.(误) 　　He hoped that his sister would lend him a hand.(正) 　　他希望妹妹能帮他。
　　He demanded me to give up the chance.(误) 　　He demanded that I give up the chance.(正) 　　他要我放弃那个机会。
　　I suggested him not to go there alone.(误) 　　I suggested that he not go there alone.(正) 　　我建议他不要单独去那里。
　　注意:有些形容词不能用于“人称代词(it除外)+be+形容词+不定式”结构，雅思写作中常用的这些形容词有:probable, impossible, easy, hard, necessary, convenient等。
　　学生常犯错误如下:
　　He is probable to make mistakes.(误)( probable的主语绝不能是人] 　　He is liable to make mistakes.(正)[ liable的主语可以是人] 　　他易于犯错。
　　I am impossible to finish it today.(误)[impossible的主语绝不能是人]。 　　It is impossible for me to finish it today.(正)[ impossible的主语可以是it]。 　　我今天不可能完成这项工作。