请教几道９８７中问题（均未讨论过）

<!--[if !supportLists]-->931. While some propose to combat widespread illegal
copying of computer programs by attempting to change people’s attitudes toward
pirating, others by suggesting reducing software prices to decrease the
incentive for pirating, and still others by calling for the prosecution of
those who copy software illegally.

(A) by suggesting reducing software
prices to decrease the incentive for pirating, and still others by calling

(B) by suggesting the reduction of
software prices to decrease the incentive for pirating, and still others call

(C) suggest the reduction of
software prices for decreasing the incentive for pirating, and still others
call

(D) suggest the reduction of
software prices to decrease the incentive for pirating, and still others by
calling（E）

(E) suggest reducing software
prices to decrease the incentive for pirating, and still others are calling

Key: E

E中and后时态与前面分句不一致，如何解释？

这道题是og160

请看解释 http://forum.chasedream.com/dispbbs.asp?BoardID=23&ID=35467

957. By law, a qualified physician can only
prescribe medicine, protecting the public.

(A) By law, a qualified physician
can only prescribe medicine, protecting the public.

(B) By law, only a qualified
physician can prescribe medicine, protecting the public.

(C) By law, only a qualified
physician can prescribe medicine which protects the public.

(D) In order to protect the public,
by law a qualified physician only can prescribe medicine.（E）

(E) In order to protect the public,
by law only a qualified physician can prescribe medicine.

Key: E

刘振民语法中提到only位置不能随意改变，如何统一到此题中来？

这道题是不是要根据逻辑意思来判断？

a qualified physician can only prescribe medicine 一个执业医师只能开处方药

only a qualified physician can prescribe medicine处方药只能由一个执业医师来开（方便理解，我把它翻成被动语态）

按法律来说，可能第二种说法更为恰当吧

然后动名词引导的短语虽然可以表目的，但是in order to 更为明确？

其实我只是根据答案来推解释，自己做也是做不对的。

请nn来解释~~

<!--[if !supportLists]-->968. Interest rates on mortgages have declined
steadily during the first six months of this year but virtually remained
unchanged during the next three months.

(A) have declined steadily during
the first six months of this year but virtually remained unchanged

(B) declined steadily during the
first six months of this year but virtually remain unchanged

(C) steadily declined during the
first six months of this year but remain virtually unchanged

(D) declined steadily during the
first six months of this year but have remained virtually unchanging’（E）

(E) declined steadily during the
first six months of this year but have remained virtually unchanged

Key: E

but后为何是现在完成时？

<!--[if !supportLists]-->985. Those who have visited the Grand Canyon have
typically seen layers of sediment in the gaping canyon, with different
colors that mark the passage of time like the rings in a tree trunk.

(A) seen layers of sediment in the
gaping canyon, with different colors that mark

(B) see layers of sediment in the
gaping canyon, whose different colors mark

(C) been seeing layers of sediment
in the gaping canyon, whose different colors are markers of

(D) been able to see layers of
sediment in the gaping canyon, with different colors marking（D）

(E) seen layers of sediment in the
gaping canyon, marking by different colors

Key: D

A错在哪里，原句中哪里体现出“be able to see”的意思？