their和theirs的后接词不同、用法不同、词性不同。their是形容词性物主代词,必须用来修饰名词,即their的后面必须接名词。theirs是名词性物主代词,相当于“their+名词”结构,所以后面不能再接名词。
their用法:their是复数第三人称的所有格形式,是复数形容词性物主代词,在句中只可用作定语,其后常接复数名词。有时为了避免显示性别,their还可代替his,her物主代词,此时其后可接单数名词。有时their还可用作动名词的逻辑主语。
theirs用法:theirs为复数第三人称的名词性物主代词,可单独使用,起名词作用,在句中可作主语、宾语或表语,但不可用作定语,无复数形式。有时theirs还可与of连用构成双重所有格。
It would cost about £3,000 toins tall a new heating systemina flat such as theirs
在他们那样的一套公寓房里安装一套新的供暖系统可能要花费3,000英镑左右。
Theirs had been a happy and satisfactory marriage.
他们的婚姻曾经一直幸福美满。
There was a big group of a dozen people at the table next to theirs.
他们旁边的桌上坐了一大群人,有十几个。
This child is no body's child until someone makes her theirs officially.
在有人办理正式手续认领以前,这个孩子不属于任何人。