请英语高手为我讲解一下哪些是人称代词,哪些是物主代词

I人 称 代 词
一、主格人称代词有I,we,you,he,she,they,it,主格人称代词就是在句中充当主语和表语的代词
1) Archibald Motley’s artistic talent 〔A〕 was apparent 〔B〕 by the time him 〔C〕 enrolled 〔D〕 in high school.
2) Legends often contain an element 〔A〕 of fact,but 〔B〕 sometimes it is 〔C〕 totally 〔D〕 untrue.
3) Unlike 〔A〕 road vehicles,Hovercrafts have no physical 〔B〕 contact with the surface over which 〔C〕 them 〔D〕 travel.
二、宾格人称代词有me,us,you,him,her,them,it,宾格人称代词即在句中充当宾语(含介词宾语)的代词
4) Let you and I 〔A〕 promise that we shall always 〔B〕 dare to do 〔C〕 what is 〔D〕 right.
5) Most of we 〔A〕 know that conductors direct their orchestras with a baton,but how many 〔B〕 are aware that 〔C〕 they also direct with their faces,hands 〔D〕 ,and shoulders?
三、例题解析
1) C错.him是宾格,而此处却需要作主语的人称代词,故应将him改为主格he.
2) C错.改为they are.C处代替的是“Legends”而不是“an element”.
3) D错.them也是宾格,应改用主格they,作定语从句中的主语,谓语为travel.
4) A错.改为me.
5) A错.改为宾格us,因为前面是介词of,us作其宾语,故用宾格.
II物 主 代 词
一、表示人的物主代词用my,our,your,his,her和their,指无生命的东西用its(但指国家时一般用she或her),它们在句中作定语
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(有弹性的) 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(橡浆) 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.
二、名词型物主代词能作表语(It's theirs)、主语(Mine is there)、宾语(I don't like hers),与of连用可以作定语(the food of theirs).
三、例题解析
1) A错.改为his.
2) B错.改为its.
3) D错.改为their.