their的名詞性物主代詞是：theirs
My trouble is nothing to theirs .我的困難比起他們來算不了什麼。
Theirs is the largest house on the block .他們的住宅是該街區最大的住宅。
I will do my part if everybody else will do theirs .要是大家都做那我也做。
Our concern and theirs substantially overlap .我們的利害關係和他們的大致相合。
That 's not the custom of theirs .那不是他們的習俗。
Our team triumphed over theirs .我們隊勝了他們隊。
I have my book ， does each student have theirs ?我已有書本了，是不是每位同學都有了
Are you a friend of theirs你是他們的朋友嗎
My value for domestic tranquility should much exceed theirs .我應該遠比他們重視家庭的平靜生活。
His position at the business was less enviable than theirs .他在公司的地位還不如他們的更令人豔羨的。
Gibbon， however， is of opinion that theirswas a valid marriage .但是，據吉本看來，這二人的婚姻是經過正當手續的。
She took up her abode in theirs for every hour that might be spent in their service .爲了隨時給他們幫忙，她搬到他們家裏來住。
The truth is that when mistakes occur ， they are more likely to be ours than theirs.其實，一旦有誤，與其說錯在他們，勿寧說錯在我們。
If some countries refuse to cut their consumption， others must reduce theirs .如果某些國家不願意降低消費，那麼其他國家必須降低他們的消費。
Despicable as the fat restaurant detective was， his crime was less than theirs .雖然那個飯店的胖偵探長行爲卑劣，但他所犯的罪卻要比他們的輕一些。
their名詞性物主代詞是theirs。
比如
These books are theirs.
這些書是他何的。
their是形容詞性物主代詞。因爲their不能單獨使用，你需要在後面跟另一個名詞。如
Their father Is a teacher.
他們的爸爸是名老師。
分辨名詞性物主代詞還是形容詞性物主代詞的依據是看該物主代詞是可以獨立使用還是需要用來修飾另一個名詞。名詞不能用來修飾名詞，而形容詞可以。
