Who is weigher than you?还是Who is heavier than you?

weigh：称...的重量, 估量...的轻重
heavy：重的, 巨大的, 沉重的, 笨重的, 过度的
谁比你更重？“Who is heavier than you?”是对的。

当然是第二个。。。
weight只当单位用吧