Tim's 远不止网友说的两层意思,它至少有5层意思:
This is Tim's book ('s 所有格,属格形式,不是缩写)
Tim's a boy. (系动词 is 的缩写)
Tim's done this. (现在完成时助动词 has 的缩写)
Tim's doing this. (现在进行时助动词 has 的缩写)
Tim's often praised by the teacher. (一般现在时被动式助动词 is 的缩写)
's 缩写是常态,表达上述含义。在书面语中,表示强调或重读时不缩写。