I've been tracking down my missing RV.我一直在寻找我丢失的房车

track down跟踪追捕； 追查

I'm trying to track down my old Aunt Maud.

我正试图寻找到我那年迈的婶婶莫德。

It took the police several days to track down their quarry.

警方用了几天时间追查到案中目标。

She's been covering for him.她一直在给他打掩护

cover for 为 ... 打掩护

His business was a cover for drug dealing.

他的商行是进行毒品交易的幌子。

Can you cover for me on friday?

星期五能不能请你替我个班？