句子成分To hand in homework on time is good.在这句话中to hand in动词不定式

句子成分
To hand in homework on time is good.在这句话中to hand in动词不定式.作什么?
在句子中：
to be作什么?
to hear from you
to go out
to leave
to see呢?抱歉,有点多了
还有,when to meet 是when 开头的疑问句加动词不定式,在句中又作什么呢?

to hand in动词不定式做主语啊.
动词不定式在句子中可做任何成分,但不能做谓语.
(1）动词不定式做主语
eg:To swim with you was very enjoyable.
注：动名词和动词不定式均可以做主语和表语,但动名词表示经常性的,抽象的动作,而不定式表示特指的一次性的具体的动作
(2）动词不定式做表语
eg:Her wish is to become a teacher.
注：表语为不定式时,主语也是不定式；当主语部分含有动词do时,做表语的不定式可以省略to.
eg:To see is to believe.
All you have to do is (to) study hard.
(3)不定式做宾语
以下及物动词后常用动词不定式：
want,decide,aim(目标),manage(试图),hope,ask,happen,like,love,choose,prevent(阻止),promise,continue,plan,learn,fail等.
eg:I decide to look for a job.
(4)动词不定式做定语
动词不定式做定语往往要后置,与被修饰词之间存在动宾关系、主谓关系、同位关系和修饰关系.如果动词不定式是不及物动词,应该在动词后加上适当的介词.如果被修饰词是地点、时间、方法,通常省略动词不定式后的介词.
eg:I have something to say.(动宾关系）
I was the last one to leave here.(主谓关系）
I have no wish to quarrel with you.(同位关系）
This is the best way to do that.(修饰关系）
I have nothing to worry about.(不及物动词后加介词）
I can't find a place to play (in).(省略介词in)
注：当名词用特定的定语如：frist,last,next,only等以及形容词最高级修饰时,后面用不定式修饰.
eg:He is the only person to know the truth.
(5）不定式做状语
不定式做状语主要表达结果、目的和原因.
eg:He worked day and night to play for the debts.(目的状语）
He woke up to find everyone gone.(结果状语）
We laughed to hear the news.(原因状语）
注：动词不定式与only连用时,可表出乎意料的结果.
eg:He went to seaside only to be drowned.
(6)动词不定式做补语
eg:Allow me to introduce her to you.