我突然想吃冰淇淋。

Wǒ tūrán xiǎng chī bīngqílín.

I suddenly wanted to eat ice cream.

外面突然下大雨了。

Wàimiàn tūrán xià dàyǔ le.

It suddenly started raining hard outside.

我突然想起我忘了带钱。

Wǒ tūrán xiǎngqǐ wǒ wàng le dài qián.

I suddenly realized I forgot to bring money.