One use of for in English is to express the number of times something happens. In Chinese this is handled with 第, just the same as with other ordinals.
You can use this to talk about the first, second, third time etc. This is referred to as the nth time.
Basics: for the nth time
Chinese tends to express this as “this is the nth time” or “that was the nth time”. There’s not a direct equivalent of “for the nth time”. So when you form this kind of sentences, you need to begin it with “this is” or “that is” etc.
Time is covered by adverbials. In Chinese word order, adverbials go before the verb. You just insert the number of times something happened after the subject and then continue with the sentence.
To express the number of times something happened, you use an ordinal number. This is formed with the structure:第 + [_number_] + 次
这是他第一次喝啤酒。 Zhè shì tā dì yīcì hē píjiǔ. He's drinking beer for the first time.
昨天是我们第二次面对面交谈。 Zuótiān shì wǒmen dì èr cì miànduìmiàn jiāotán. We spoke face to face for the second time yesterday.
我要第三次去巴黎。 Wǒ yào dì sāncì qù bālí. I will go to Paris for the third time.
As you can see, all you have to do is add 第 + number + 次 after the subject, and you’re done.
For the nth time in …
You can also express that something happens for the nth time in a period of time. This could be something like “for the first time in two years” or “for the third time this week”.
To do this, you just have to insert the length of time before the ordinal. So now the phrase you’re going to insert has this structure:[_length of time_] + 中 + 第 + [_number_] + 次
This is inserted right after the subject, as above. It expresses “for the nth time in length of time”.
我十年中第一次见了她。 Wǒ shí nián zhōng dì yīcì jiànle tā. I saw her for the first time in ten years.
我人生中第二次杀了人。 Wǒ rénshēng zhōng dì èr cì shāle rén. I killed someone for the second time in my life.
我们的军队这年代中第三次打仗。 Wǒmen de jūnduì zhè niándài zhōng dì sāncì dǎzhàng. Our soldiers will go to war for the third time this decade.
Words other than 中 can be used to express “in”. Some examples:
这是我这个月第四次把我的手机弄丢了。 Zhè shì wǒ zhège yuè dì sì cì bǎ wǒ de shǒujī nòng diūle. I've lost my phone for the fourth time this month.
美国历史上第一次用了核武器。 Měiguó lìshǐ shàng dì yīcì yòngle héwǔqì. America used nuclear weapons for the first time in history.
For the last time
You might also want to express that something happened for the last time, rather than a particular number. The structure for this is very similar. Rather than a ordinal number, just use 最后.
那是我最后一次犯那个错误。 Nà shì wǒ zuìhòu yīcì fàn nàgè cuòwù. I've made that mistake for the last time.
我们已经见了她最后一次。 Wǒmen yǐjīng jiàn le tā zuìhòu yīcì. We've seen her for the last time now.
他们最后一次离开城市。 Tāmen zuìhòu yīcì líkāi chéngshì. They're leaving the city for the last time.
Adding in more details
You can also add in other adverbials such as time, manner and place. These go in between the subject and verb, just like other adverbials.
我昨晚第一次看了恐怖电影。 Wǒ zuó wǎn dì yīcì kànle kǒngbù diànyǐng. I saw a horror film for the first time last night.
我第一次用汉语点了菜。 Wǒ dì yīcì yòng hànyǔ diǎn le cài. I've ordered a meal in Chinese for the first time.
我第一次看到她是在格兰路。 Wǒ dì yīcì kàn dào tā shì zài gé lán lù . I saw her for the first time on Raglan Road.
If you have any questions or suggestions, please share them in the comments below.