Expressing Before, After and While Somethings Else Happens

Before & After - yǐqián & yǐhòu:

Phrase + yǐqián/yǐhòu + action
- before/after the phrase happens, the action happens

yīge xiǎoshí yǐhòu, wǒ huì hé péngyou qù kàn diànyǐng. ——> One hour after (that), I will go watch a movie with my friends ——> I will go watch a movie with my friend after one hour. 一个小时以后，我会和朋友去看电影。

wǒ zǎoshàng bādiǎn yǐqián, hē le yībēi kāfēi. ——> I morning at 8 o’clock before (that), drank a cup of coffee. ——> I drank a cup of coffee before 8am. 我早上八点以前，喝了一杯咖啡。

māma huíjiā yǐqián, wǒ xiǎng qù chāoshì mǎi yīxiē cài. ——> Mom returns home before (that), I want to go to the market to buy some food. ——> Before mom returns home, I want to go to the market to buy some food. 妈妈回家以前，我想去超市买一些菜。

While...  -  ...de shíhou:

Phrase + de shíhòu + action
- while the phrase happens, the action also happens.

shàngwǔ shídiǎn de shíhòu，wǒ zài tīng yīnyuè . ——>10 o’clock in the morning while that happened, I am listening to music. ——>While it’s 10am, I am listening to music. 上午10点的时候，我在听音乐。

wǒmen shàng zhōngwén kè de shíhòu，zhǐ kěyǐ shuō zhōngwén. ——>We are attending Chinese class while that happened, (we) can only speak Chinese. ——> While attending Chinese class, we can only speak Chinese. 我们上中文课的时候，只可以说中文。

bàba zài kāichē de shíhou，érzi zài yòng shǒujī. ——> Dad is driving while that happened, the son is using the phone. ——> While dad is driving, the son is using the phone. 爸爸在开车的时候，儿子在用手机。

Note1：For the first and second sentences, since the subject is the same, we only need one in the sentence. You can place it either in the front of the phrase or at the beginning of the action. However, if we have two different subjects, we will keep both subjects. Note2：The phrases can be actions (kāichē, zuòfàn, mǎicài etc.), time durations (30 fenzhōng, yīge xiǎoshí, yīge xīngqī etc.), time words (xīngqīyī, wǎnshàng bādiǎn, míngtiān etc.) or ages (10 suì etc.)