不定式to do 在句子中是名词成分吗?

equire 后只能接一件事.
即require sth,至于require doing 其实是
require （of可省略） doing,of doing 即为sth

不定式表将来或者表目的
V-ing 作主语时表动名词 作非谓语动词时表主动

to是介词 prep

感官动词 see, watch, notice, look at,
hear, listen to, smell, taste, feel +doing 表示动作的进行性; 感官动词+ do表示动作的完整性,（动词不定式省略to),如
I
saw him play in the park yesterday.
昨天我看见他在公园里玩了.（强调"我看见了"这个事实）
I
saw him playing in the park yesterday.
昨天我看见他正在公园里玩耍. （强调"我见他正玩"这个动作）

对,不是特殊情况下都是.
不定式定义：由to+动词原形构成.不定式是一种非限定性动词.而非限定性动词是指那些在句中不能单独充当谓语的动词,可分为不定式,动名词,现在分词和过去分词.“动词不定式”由动词+不定式构成.动词不定式在句中可以作句子除谓语之外的任何句子成分.动词不定式的被动形式除了一般形式外还有其完成式和进行式.

get 后跟to 表示马上去做之前未做的事情
get后还可加done,表被动语态

Who do you get to go with you?
你让谁和你一起去?
I don't know who to believe.
我不知道可以相信谁.

动词不定式是有表示将来的意思.但是跟所在句子的语态没有关系.在你的这个句子中是表示过去要做某事,要做某事可以说是现在要去做,将来要去做,过去曾经打算要去做的!不定式只是表达要去干嘛的意思,至于是不是将来要去就要看句子的语态.像你举的例子,便是过去的语态.

to do 是后置定语 .nothing是to do 的逻辑宾语
类似结构：I have nothing to do.
My mother has a lot of housework to do.
I have something to buy.
意思是“有……要做”

动名词可以作逻辑主语吗?
Answer:
动名词是三大非谓语动词之一,它由动词变化而来本身既有动词性又有名词性.
所以动名词不仅可以做主语,还可以在句中作宾语和表语(详情可以参考语法书关于非谓语动词-动名词用法的讲解,这里就不再赘述)
关于动词不定式和动名词作主语的区别,可以参考以下网络回复:
If you still feel confused,leave a message please

want,would like/love,decide,agree,promise,hope,wish,learn,plan,refuse,ask,advise,discuss,know,teach等

英文是很讲究逻辑的语言.主动和被动的定义,相信你非常了解.我拿一个句子做例子：There is not much to see.(没啥值得看的东西）其实,这句话,合理的句型应该是：There is not much to be seen. 要不然,就应该是：There is not much for us to see. 在口语中,这句话的for us被省略了,就成了There is not much to see.希望我简短的答复你能满意.

e considered to do这是一个句式,后面的是have done 完成时态,完成时态才是要考虑的

dread, hate, like, love, prefer, begin, cease, commence, continue,
start, forget, remember, regret, choose, hope, intend, mean, plan, propose, want, wish,
help, scorn, venture, ask, beg,
decline, demand, offer, promise, refuse, swear, undertake, affect, claim, profess,
afford, attempt, contrive, endeavor, fail, learn, manage, neglect, omit, try

to do 中的to 不是介词,而是动词不定式符号.
He slipped out,pulling the door to.
他溜了出去,虚掩上门.
这里的to是副词 表示的意思是：ADV(门)关着,虚掩着
就记住这么一个特例,其他的to全部都是介词.

doing 表示一贯性经常的动作.如 teaching is my job.
to do表示一次性将来的动作.To clean the classroom this aftenoon is our task.

1.seem+形容词 Everything seems easy.一切似乎很容易.2.seem+名词 He seemed an honest man.他看上去像是个老实人.This seemed to us an ideal plan.我们感到这是个完美的计划.3.seem+不定式 The maths problem seems to be very difficult to work out.这道数学题似乎很难解决.I seem to have caught a cold.我好像是感冒了.4.seem+过去分词 Our teacher seemed stopped by the question.我们的老师似乎是被那个问题难住了.His story seemed revealed.他的谎言似乎已被揭露.5.seem+doing No one seemed thinking that way.似乎没人那样想.She seemed lacking in enthusiasm when we were talking about that film.我们谈论那部电影时,她看来好像没多大热情.6.seem+like+n./ V-ing,意思是"看起来像……" It seems like years since I last saw you.自从我上次见到你以后,好像是过了好几年.Those cards seemed like so many little flags dotted about the schoolroom.那些卡片好像许多面小旗点缀着教室.7.There seems to be...,意为"似乎有；好像有……" There seems to be no work for you to do now.看来现在没有工作需要你做了.8.It seems/seemed +that从句 It seems that he is lying.看来他在撒谎.It seemed that no one knew what happened.看来没有人知道发生了什么事.9.It seems/seemed + as if从句 It seems as if he were in a dream.看来他像是在做梦.It seemed as if the good man were trying to teach us all he knew at this last lesson.这个好心人仿佛要在最后这一堂课上把他的全部知识教给我们.参考资料：http://disk.myblog.cn/user1/2579/archives/2005/2313.shtml