You use again to indicate that something happens a second time, or after it has already happened before.
He kissed her again.
他再一次亲了她。
Again there was a short silence.
又有一阵短暂的沉默。
You use again to indicate that something is now in a particular state or place that it used to be in.
He opened his attaché case, removed a folder, then closed it again.
他打开了他的公文包,拿出了一个文件夹,然后又把它合上了。
You can use again when you want to point out that there is a similarity between the subject that you are talking about now and a previous subject.
Again the pregnancy was very similar to my previous two.
同样,这次怀孕和我前两次的情形非常类似。
You can use again in expressions such as but again, then again, and there again when you want to introduce a remark that contrasts with or weakens something that you have just said.
You may be happy to buy imitation leather, and then again, you may wonder what you're getting for your money.
你可能乐于买仿制皮革,但你也许又想知道你花的钱是否物有所值。
You can add again to the end of your question when you are asking someone to tell you something that you have forgotten or that they have already told you.
Sorry, what's your name again?
对不起,再问一次,你叫什么名字?
You use again in expressions such as half as much again when you are indicating how much greater one amount is than another amount that you have just mentioned or are about to mention.
A similar wine from France would cost you half as much again.
类似的法国葡萄酒会多花你一半的钱。
again and again , time and again
You can use again and again or time and again to emphasize that something happens many times.
He would go over his work again and again until he felt he had it right.
他会反复检查他的工作,直到觉得准确无误为止。