idiom成语；in（介词）关于；understand one’s difficulties in sth.【理解......方面，你遇到困惑】
literary works文学作品；be troubled by...【受到......困惑不解】
It is +adj.for sb to do sth.【做某事是......】=It is +adj. that sb（主语）do（谓语） sth.
It is common for sb to do sth【对某人来说，做某事是常见】=It is common that sb do sth某人做某事是常见的
The students can do it. Let alone teachers，+句子...。
It is good for teachers. Let alone for students，+句子...。
It is hard to do it. Let alone to finish it，+句子...。
Share A with sb=share with sb A
I am very tall
The book is on the desk.
to the greatest extent【在最大程度上（状语）】
Please feel free to write back if...【如果......，请随时回信】
I fully understand your difficulties in learning Chinese idioms. It is even common for Chinese people to be troubled by idioms when they read literary works. Let alone for foreigners，I would be happy to share with you strategies that we Chinese learn idioms.
The best way of learning idioms is through reading. Only by reading more and accumulating more can you master idioms to the greatest extent. Besides，having a Chinese Idiom Dictionary can be a good choice so that you can refer to it when you come across idioms you can’t understand in reading.
I hope my advice can help you. Please feel free to write back if you have anything more to discuss.