用不定式改写这句话 "I was sorry when I heard that",请问各位改写不定式有诀窍吗?

用不定式改写这句话 I was sorry when I heard that,请问各位改写不定式有诀窍吗? I haven't decided which train I should take.(用动词不定式改写句子)顺便解释一下什么是动词不定式 这个动词不定式在句中是什么成分I was surprised to find hardly anyone there.这句话里的动词不定式to find hardly anyone there在句中作什么成分? 英文改写!It was very hot.I could not sleep last night(用so...that改写) We thought this was a good place for a picnic{用动词不定式改写}-----was a good place for us ----a picnic一线一词啊 it was in the United States that I made the acquaintance of professor jones 请把这句话用make one's acquaintance of sb 改写 主要是one's那里用什么形式 用动词不定式改写下列句子1.the accident was so terrible that we can`t talk about it2.was cortes the first european who ever saw the pacific ocean?3.here is something that you can do while you`re waiting4.i haven`t decided whether i shall a the best way to do this was to become a flight attendant.这句话为什么用了两个不定式?它们都有什么作用?第二个不定式能用动名词代替么? i was also afraid to speak in class afraid为什么不加to用不定式呢 问一个关于with复合结构的问题1）It was going to be a problem for her to get off the train with two small children to be taken care of.2) There I was,with nothing to take care of.在上面这两句话中,用的都是with sth.+不定式的 动词不定式的被动语态这句话用英语怎么说 I went to bed early because I was tired 用so改写此句 I started collecting coins when I was thirty.(用since改写） I started collecting coins when I was thirty.(用since改写) Dieu merci,accorder un ange pour moi.Je lui trésor.Baby,je t'aime!这句话上面意思, I didn't know how to do it问题I didn't know how to do it这句话中为什么有to?是不定式吗?如果是,那为什么要用不定式表达? I was bought something.这句话对吗? I don't know when l shall start the work.(用动词不定式改写）I don't know when _____ _____ the work.