wǒ / shàng / zhōu / shōu / dào / nǐ / de / xìn / ， / jīn / tiān / zhōng / yú / yǒu / shí / jiān / fù / xìn / le / 。

我上周收到你的信，今天终于有时间复信了。

I received your letter last week and finally have time to reply today.