他们昨晚发生关系了。
他們昨晚發生關係了。
tā men zuó wǎn fā shēng guān xi le 。
They made love last night.
Examples (Wiktionary)
Mandarin
发生关系
發生關係
fā shēng guān xì
to have sexual relations
Mandarin
共产党员在和友党友军发生关系的时候，应该坚持团结抗日的立场，坚持统一战线的纲领，成为实行抗战任务的模范；应该言必信，行必果，不傲慢，诚心诚意地和友党友军商量问题，协同工作，成为统一战线中各党相互关系的模范。
共產黨員在和友黨友軍發生關係的時候，應該堅持團結抗日的立場，堅持統一戰線的綱領，成為實行抗戰任務的模範；應該言必信，行必果，不傲慢，誠心誠意地和友黨友軍商量問題，協同工作，成為統一戰線中各黨相互關係的模範。
gòng chǎn dǎng yuán zài hé yǒu dǎng yǒu jūn fā shēng guān xì de shí hou ， yīng gāi jiān chí tuán jié kàng rì de lì chǎng ， jiān chí tǒng yī zhàn xiàn de gāng lǐng ， chéng wéi shí xíng kàng zhàn rèn wù de mó fàn ； yīng gāi yán bì xìn ， xíng bì guǒ ， bù ào màn ， chéng xīn chéng yì de hé yǒu dǎng yǒu jūn shāng liang wèn tí ， xié tóng gōng zuò ， chéng wéi tǒng yī zhàn xiàn zhōng gè dǎng xiāng hù guān xì de mó fàn ．
In their relations with friendly parties and armies, Communists should take a firm stand of unity for resistance to Japan, uphold the programme of the united front and set an example in carrying out the tasks of resistance; they should be true in word and resolute in deed, free from arrogance and sincere in consulting and co-operating with the friendly parties and armies, and they should be models in inter-party relations within the united front.
Mandarin
因为书若是买来“摆美”，不去读它，或把名贵的书锁起来怕孩子弄脏弄坏，那它就不会与孩子“发生关系”，也失去了买书的意义。
因為書若是買來“擺美”，不去讀它，或把名貴的書鎖起來怕孩子弄髒弄壞，那它就不會與孩子“發生關係”，也失去了買書的意義。
yīn wèi shū ruò shì mǎi lái “ bǎi měi ” ， bù qù dú tā ， huò bǎ míng guì de shū suǒ qǐ lái pà hái zi nòng zāng nòng huài ， nà tā jiù bù huì yǔ hái zǐ “ fā shēng guān xì ” ， yě shī qù le mǎi shū de yì yì ．
Because if the books are bought just for decoration and you don't read them, or if you lock up precious books in fear of your children dirtying or ruining them, the books won't "develop a relationship" with your children, and you missed the point of buying books.