介词选择填空,有些很相近,应该怎么区别呢?选哪个合适为什么?

题目

介词选择填空,有些很相近,应该怎么区别呢?选哪个合适为什么?
1.we deal in decorative fabrics in/of different varieties.
2.good harvest this year has made it possible for us to supply walnuts at/against last year's pirce.
3.since/because/owing to heavy commitments,we cannot accept any fresh orders.

答案

1.We deal in decorative fabrics of different varieties.2.Good harvest this year has made it possible for us to supply walnuts at at last year's pirce.3.Owing to heavy commitments,we cannot accept any ...