but

It’s an old car, but it’s very reliable.

这是一辆旧车，但是性能非常可靠。

They rushed to the hospital, but they were too late.

他们急忙赶到医院，但是已经太迟了。

We’ve invited the boss, but she may decide not to come.

我们邀请过老板，但她有可能决定不来。

an expensive but extremely useful book

价钱很贵却是非常有用的一本书

‘Has he got any experience?’ ‘No, but he’s keen to learn.’

“他有经验吗？”“没有，但他非常好学。”