Four teams of three people would compete ______ the game andthe winners would receive a free vacation

I had ______ unusual experience on Sunday.

u offers visitors outstanding natural beauty coupled with excellent customer service, _________ makes for an unforgettable experience.

填入下面一段文字横线处的语句，最恰当的一句是 （ ）血栓闭塞性脉管炎又称“脉管炎”，虽是一种血管的炎症，但并不是细菌感染引起的的，而是血栓阻塞血管、血流减少所致，主要以下肢为主。脉管炎后期可引起手足发黑、坏死。但 ，如果在早期能明确诊断，及时治疗，可以避免发生严重的后果。

下列加点的熟语使用恰当的一项是 （ ）