which 原句是 we can see and talk to our friends through the vision phone.再给一题。Who is the man whom you said hello just now 这题是改错的，有人说可以在hello 加 to , 可不可以改whom为that就是在 HELLO后面加TO也可以改WHOM为THAT为什么呢？能解析一下吗?the man 是后面那句的宾语 said缺少介词 所以要加To 而这个宾语还是人 所以也可以用that