it's not that , it's not just that
You use it in expressions such as it's not that or it's not just that when you are giving a reason for something and are suggesting that there are several other reasons.
It's not that I didn't want to be with my family.
并不是因为我不愿意和我的家人在一起。
You use it to refer to an object, animal, or other thing that has already been mentioned.
It's a wonderful city, really. I'll show it to you if you want.
这确实是座很棒的城市。如果你愿意的话,我可以带你到处看看。
My wife has become crippled by arthritis. She is embarrassed to ask the doctor about it.
我妻子因患关节炎腿瘸了。她不好意思去向医生询问相关病情。
You use it to refer to a child or baby whose sex you do not know or whose sex is not relevant to what you are saying.
She could compel him to support the child after it was born.
她可以迫使他在孩子出生后抚养孩子。
You use it to refer in a general way to a situation that you have just described.
He was through with sports, not because he had to be but because he wanted it that way.
他放弃体育运动了,不是因为他非放弃不可,而是因为他想要那样。
You use it before certain nouns, adjectives, and verbs to introduce your feelings or point of view about a situation.
It was nice to see Steve again.
很高兴又见到了史蒂夫。
It's a pity you never got married, Sarah.
萨拉,很遗憾你从来没有结过婚。
You use it in passive clauses that report a situation or event.
It has been said that stress causes cancer.
据说压力会诱发癌症。
You use it with some verbs that need a subject or object, although there is no noun that 'it' refers to.
Of course, as it turned out, three-fourths of the people in the group were psychiatrists.
当然,结果证明这些人中有四分之三是精神病医生。
You use it as the subject of 'be' to say what the time, day, or date is.
It's three o'clock in the morning.
现在是凌晨3点。
It was a Monday, so she was at home.
那天是星期一,所以她在家。
You use it as the subject of a linking verb to describe the weather, the light, or the temperature.
It was very wet and windy the day I drove over the hill to Del Norte.
那天风雨交加,我开车翻过小山去德尔诺特。
You use it when you are telling someone who you are, or asking them who they are, especially at the beginning of a phone call. You also use it in statements and questions about the identity of other people.
'Who is it?' he called.—'It's your neighbour.'
“谁呀?”他喊道。—“你的邻居。”
When you are emphasizing or drawing attention to something, you can put that thing immediately after it and a form of the verb 'be'.
It's really the poor countries that don't have an economic base that have the worst environmental records.
确实是那些没有经济基础的贫穷国家的环保记录最糟糕。