我喜欢狗，但是我对猫过敏。

I like dogs, ___but I'm allergic to cats.

这本书很有趣，但是有点长。

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

你可以邀请基思，但请不要问他的朋友。

You can invite Keith, ___but please don't ask his friend.