How do you say

I bought a new sofa last week, which is very comfortable.

..in Chinese?

我上周买了一张新沙发,非常舒适。

wǒ shàng zhōu mǎi le yī zhāng xīn shā fā , fēi cháng shū shì 。

How do you say "It’s the coldest time of winter in Beijing." in Chinese?