__ one of his classmates.A.On B.From C.In D.Of. 这个句子前面本身就缺前面一段.所以我们假设一个完整的句子.你看意思是什么样子的.We have found the murder weapen on one of his classmates.我们在他同学的身上找到了凶器(凶器被找到时,正带在身上)We have found the murder weapen from one of his classmates.我们在他同学那里找到了凶器(凶器被找到时,可能不在身上,可能在他屉子里)We have found the murder weapen in one of his classmates.我们在他同学那里发现了凶器(凶器被找到了,但我们不说是从哪一个人那得到的)We have found the murder weapen of one of his classmates.这局话给我理解,语法有问题.硬要理解,就是:我们发现他其中一个同学就是凶器.He saw a cat climbing up the tree __ __.这里可以填that day吗?可以填 that day 意思是, 那天,他看见一只猫爬树.