一、表示人的物主代詞用my， our， your， his， her和their，指無生命的東西用its(但指國家時一般用she或her)，它們在句中作定語

二、名詞型物主代詞能作表語(It‘s theirs)、主語(Mine is there)、賓語(I don’t like hers)，與of連用可以作定語(the food of theirs)。

三、同步練習

1) A scientist bases its [A] work on hypotheses that [B] have been checked [C] through careful [D] experimentation.

2) Crude rubber is an [A] elastic(有彈性的) solid with a specific gravity of 0.911 and a refractive index(折射率) of 1.591， though it [B] composition varies with different latexes(橡漿) as well as [C] with the way it is prepared [D] at the plantation.

3) Manufacturers [A] of consumer goods [B] often change [C] the styles of them [D] products.

四、例題解析

1) A錯。 改為his.

2) B錯。 改為its.

3) D錯。 改為their.