动名词作主语和动词不定式做主语的区别?

Ⅰ.动名词和不定式做主语的相同点
1.不定式短语和动名词做主语时，常常为了保持句子的平衡，用it来做形式主语，如：
It is not easy to learn English well.
It is no use asking him for help.
2.如果主语用了不定式,表语和宾语也要用不定式;主语用了动名词,表语和宾语也要用动名词,这在英语中称为对称性,如:
To see is to believe. = Seeing is believing. (眼见为实)
(85)It is better to stay home than _A__ out.
A. to go B. going C. go D. gone
Ⅱ.动名词和不定式做主语的不同点
1.不定式做主语常表示具体的某一动作;表示泛指或一般的抽象的概念时,多用动名词,如:
(92)_B_ is a good form of exercise for both young and old.
A. The walk B. Walking C. To walk D. Walk
2.在”There/It +be+ no use(good/help/need)”之后常用动名词做主语,而少用不定式,如:
It /There is no use crying over the split milk.
It /There is no help taking this medicine.
★但是如果该句型中用了for引出不定式的逻辑主语,就只能用不定式,如:
(93) There is no good for us to do that exercise.
3.不定式可以和when, where, how, what, whether等连用,在句子中做主语,宾语和表语,而动名词则不能,如:
How to solve the problem is a hot potato.
Where to put the box seems hard to decide.
Whether to do it hasn’t been decided.
What to do next is up to you.

不定式（to do形式）和动名词（动词ing形式）做主语的区别

不定式作主语时常用it作形式主语
避免句子头重脚轻，保持句子平衡
It (形式主语）took me only 20 minutes to finish the job（真正主语）。
带有疑问词的动词不定式在句中做主语，其功能相当于名词性从句。
Where to hold the singing contest（主语） has not been
decided yet.
= Where we shall hold the singing contest（主语从句） has not
been decided yet.
当动名词有逻辑主语时，常在前面加一个名词或代词的所有格，构成动名词的复合结构
(名词或代词的所有格是动名词的逻辑主语)
口语中，动名词复合结构作宾语，物主代词常用人称代词宾格，名词所有格常用名词普通格来代替
动名词复合结构在句首作主语时必须用物主代词或名词所有格
Helen’s being ill made her parents upset

阿萨德发撒啊啊啊啊啊

不定式作主语时常用it作形式主语
避免句子头重脚轻，保持句子平衡
It (形式主语）took me only 20 minutes to finish the job（真正主语）。
带有疑问词的动词不定式在句中做主语，其功能相当于名词性从句。
Where to hold the singing contest（主语） has not been
decided yet.
= Where we shall hold the singing contest（主语从句） has not
been decided yet.

当动名词有逻辑主语时，常在前面加一个名词或代词的所有格，构成动名词的复合结构
(名词或代词的所有格是动名词的逻辑主语)
口语中，动名词复合结构作宾语，物主代词常用人称代词宾格，名词所有格常用名词普通格来代替
动名词复合结构在句首作主语时必须用物主代词或名词所有格
Helen’s being ill made her parents upset

不定式有表达将来的意思。现在分词是对客观事实陈述。