All of this is proving effective and there is now some loosening of restrictions as new cases slow. 出自中国日报。作系动词的 prove 可以用进行时吗?我记得只有 feel、look 以及表示变化的系动词才可以用进行时吧。
it was a storage jar made of earthenware, no doubt discarded because a break had made it useless.这句中连接词是什么?是which is的省略吗?定语从句中可以省略which is的所有情况,以及非限定中可不可以省略which is?