今天的雾很大。

Jīntiān de wù hěn dà.

The fog is very heavy today.

山上的雾很大。

Shānshàng de wù hěn dà.

The fog on the mountain is very thick.

外面很大雾，开车要小心。

Wàimiàn hěn dàwù, kāichē yào xiǎoxīn.

It's foggy outside, be careful when driving.