孩子们在游乐园玩得非常开心。

The kids were ___happy playing at the amusement park.

我很乐意帮你搬这些箱子。

I'd be ___happy to help you carry these boxes.

真是个幸运的巧合，我们居然在同一班飞机上相遇了。

It was a ___happy accident that we ended up on the same flight.

他对新工作非常满意。

He is very ___happy with his new job.