be +不带to的不定式是强调形式吗?for example ：All you have to do is study hard.

be +不带to的不定式是强调形式吗?for example ：All you have to do is study hard.
be +不带to的不定式是强调形式吗?
for example ：
All you have to do is study hard.

be +不带to的不定式是强调形式吗?for example ：All you have to do is study hard.
不是强调句,这是省略动词不定式符号 to的一种形式
注：不定式作表语时to可以省略
The task is finish the grammar exercises.
下面举出其他省略to的几种形式,
一 不定式符号to的省略
I.感官动词和使役动词后的to省略
see/watch/notice/observe/feel/hear/listen to/make/have/let +sb do sth.
They knew her very well,for they had seenher grow up.
I will have Mary wash her clothes herself.
II.help 后to可省略,也不可省略
why 的句式
Why worry about such foolish things?
Why not leave her a message?
IV.had better + do,would rather do ….than + do
I’d rather watch TV at home than go to see a film.
一个句子有两个不定式时,后面的不定式to省略
It’s necessary for us to read more and have morepractice.
He didn’t want to go on working but have a rest.
VI.不定式作表语时to可以省略
The task is finish the grammar exercises.
VII.介词but ,except后的to是否省略,要看它前面是否有实意动词do,如有实意动词do,
but ,except后的to省略,
如没有实意动词do,but ,except后的to不省略.
1.There is nothing to do but /except waittill it stops raining.
2.He could do nothingbut /except cry.
3.Tom could donothing but /except stay home.
* He couldn’t choose but 4.Tom has no choice but/except to stay home.
Mary had no choice but /except lie in bed.
VIII.can’t help but do sth = can’t help doing
1.He couldn’t help but laugh.
2.I can’t help but wonder what he is thinking.
IX.can’t but do = have to do 1.I can’t but wait here.
2.There being no bus,he couldn’t but walk home.
X.can’t choose but do =have no choice but to do =have to do
1.He couldn’t choose but accept his offer.=
He had no choice but to accept his offer.
二.不定式符号to不省略,to后面的动词省略避免重复.
I.like/love/hope/wish/mean/want/refuse/manage/expect/
forget/remember/agree+ to do.
1.---Would like to go to the cinema?
-----Yes,I’d like/love/hope to.
2.---Why didn’t you tell him earlier?
----I meant to,but I forgetabout it.
The customer was asked to pay another $10,but he refused to.
参考资料：百度文库

不是强调形式。语法书上的解释是：当不定式做表语时，to 可以省略。

All you have to do is study hard.这个句子有问题。
应该为：All you have to do is to study hard.或All you have to do is studying hard.

这个句子有问题吧...