He has to visit them on the sly.

他只得偷偷地去看望他们。

Under the cover of the smog, He snatched the pot on the sly.

在烟雾的掩护下，他偷偷地拿走了那只壶。

Some boys smoke on the sly.

有些男孩子暗地吸烟。

Some officials claimed to unhook connections with the companies but still maintained close ties on the sly.

某些干部口称已跟公司脱钩， 可暗中仍然保持联系。

I've tipped you a wink or signalled to you on the sly many times, but before you took the hint others had already noticed.

我多次向你使眼色，又给你递暗号，别人都明白了，你却没有反应。