我今天特别想吃薯条，于是我去了麦当劳。

Wǒ jīntiān tèbié xiǎng chī shǔtiáo, yúshì wǒ qù le Màidāngláo.

I especially wanted to eat fries today, thus I went to McDonalds.

我忘了带钱包，于是他帮我付钱了。

Wǒ wàng le dài qiánbāo, yúshì tā bāng wǒ fùqián le.

I forgot to bring my wallet, hence he helped me pay.

我跑步的时候突然下大雨了，于是我全身湿透了。

Wǒ pǎobù de shíhou tūrán xià dàyǔ le, yúshì wǒ quánshēn shītòu le.

When I was running it suddenly started raining hard, as a result I was completely soaked.