自从开始新工作后，他开心多了。

He's been much happier ___since he started his new job.

我从蒂姆七岁起就认识他了。

I've known Tim ___since he was seven.

读这封邮件时我很惊讶，因为自从去年拜访你后我就没收到你的消息了。

I was really surprised when I read the e-mail because I haven't heard from you ___since I visited you last year.