How do you say

Changsha’s weather will be unstable for the next three months, with hot spells and cold ones.

..in Chinese?

未来三个月内,长沙的天气将会反复无常,时冷时热。

wèi lái sān gè yuè nèi , cháng shā de tiān qì jiāng huì fǎn fù wú cháng , shí lěng shí rè 。

How do you say "I bought a new sofa at a furniture store." in Chinese?