(2)作目的状语或者在形容词后作状语，一般用不定式。如：
[例21] _______ (complete) the project as planned, we’ll have to work two more hours a day.
解析：因句中已有谓语will have to work，所以complete应为非谓语动词；因“(为了)按计划完成这项工程”是“我们每天不得不额外多工作两小时”的目的，作目的状语，用动词不定式，故填To complete。
[例22] Some people say that oldest children, who are smart and strong-willed, are very likely ___33 (succeed). (2008年佛山一模)
解析：因在形容词likely后作状语，要用动词不定式，故填to succeed。
3)作伴随状语，常用分词，与逻辑主语是主动关系，用现在分词，是被动关系，用过去分词。
[例23] He saw the stone, 37 (say) to himself: “The night will be very dark.” (2008年东莞一模)
解析：句中已有谓语saw，所给动词与saw不是并列关系，应当是非谓语动词；又因He与say是主动关系，故填saying作伴随状语。
[例24] The headmaster went into the lab, ________ (follow) by the foreign guests.
解析：句中已有谓语went，而follow又不是与之并列的，故为非谓语动词；又因the headmaster与follow是被动关系，故用过去分词作伴随状语。
(4)不论非谓语动词在句中作何种成分，若判断需要用分词，与逻辑主语是主动关系用—ing形式，是被动关系用—ed形式。
[例25] There will be a meeting, __40__ (start) later this year to review the film. (2008年广州二模)
解析：因a meeting与start是主动关系，用现在分词短语作定语，补充说明a meeting，故填starting。
[例26] Lessons 39 (learn) in sports can help us in our dealing with other people. (广东考试说明)
解析：因句中已有谓语can help，所以learn应为非谓语动词；又因lesson与learn是被动关系，要用过去分词短语作定语，故填learned。
特别提醒：有时给出的动词可能既不是谓语动词也不是非谓语动词，而是要求词类转换。如：
But Jane knew from past experience that her ___36___ (choose) of ties hardly ever pleased her father. (2009年广东)
分析：括号中所给词choose虽然是动词，但在句中作主语，且在形容词性物主代词后，应当填choose的名词形式choice。
3)词类转换题根据该词在句子所作句子成分确定用哪种形式。
①作表语、定语或补语，通常用形容词形式。如：
[例27] The youngster immediately fell ________ (silence) as tears flew down from his big blue eyes.
解析：因在系动词felt后作表语，用形容词，故填silent。
[例28] In a ________ (danger) part of the sea off the coast of New Zealand, they learnt to…
解析：在冠词与名词之间，要用形容词，作定语，故填dangerous。
例29] Teachers must try their best to make most of their students ________ (interest) in the subject.
解析：因所填词在句中作宾语most of their students的补足语，用形容词；表示“感兴趣”，填interested。
例29] Teachers must try their best to make most of their students ________ (interest) in the subject.
解析：因所填词在句中作宾语most of their students的补足语，用形容词；表示“感兴趣”，填interested。
②作主语，或在及物动词或介词后作宾语，用名词形式。
[例30] When China’s ancient scientific and technological ________ (achieve) are mentioned, the nation will generally refer to the Four Great Inventions.
解析：在时间状语从句中，要求填的词作主语，China’s ancient scientific and technological是主语的定语；作主语要用名词，又由are可知，主语是复数，故填achievements。