We have to clean the house ( ) time to time.

问题描述:

We have to clean the house ( ) time to time.

from
时常

fromfrom time to time 是一个固定短语,不时;偶尔;间或 的意思例:I go shopping from time to time.我时常去购物.You are required to check back this page from time to time.你们必须时常来这个网页查看(公告啊...