How do you say

He shed twenty pounds in three months in preparation for a marathon.

..in Chinese?

他在三个月内瘦了二十斤,为马拉松比赛做好了准备。

tā zài sān gè yuè nèi shòu le èr shí jīn , wèi mǎ lā sōng bǐ sài zuò hǎo le zhǔn bèi 。

How do you say "I want to buy a new sofa for the living room." in Chinese?