but then (again)

after all; on the other hand (introducing a contrasting comment)

另一方面，然而

it couldn't help, but then again, it probably couldn't hurt.

它没什么用，不过可能也没危害。

then and there

immediately

当场，立即

and then some【非正式用语】

With considerably more in addition

而且远不止此

This project will take all our skill and then some.

这个工程将采用我们所有的技术，而且远不止此