Are you free after school?—worry, I’ve planned to treat a friend of mine to dinner ____ for help[ ]

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。

Tom was over there. His red clothes stood out clearly_____the snow.

I can think of many cases ______students obviouslyknow a lot of English words and expressions but couldn’t write a good essay .

n pulled out a gold watch,_____weremade of small diamonds.