but

我上周末想去看你，但我感冒了。

I wanted to visit you last weekend, ___but I caught a cold.

他们希望今年夏天出国旅行，但他们负担不起。

They hoped to travel abroad this summer, ___but they couldn't afford it.

这本书很有趣，但是有点长。

This book is interesting, ___but it's a bit long.