所以

yīn wèi xià yǔ le suǒ yǐ wǒ men jué dìng dài zài jiā lǐ

因为下雨了，所以我们决定待在家里。

Because it was raining, we decided to stay at home.

diàn huà chū le gù zhàng suǒ yǐ tā dǎ bù tōng

电话出了故障，所以他打不通。

Telephones are down so he can't get through.

méi yǒu zuò wèi le suǒ yǐ wǒ zhǐ hǎo zhàn zhe

没有座位了，所以我只好站着。

There were no seats left so I had to stand up.

wèn qīng suǒ yǐ

问清所以

ask about the true reason