天山新题 中的几道题目，望G友们指点！！！

各位G友，麻烦指点以下几题 ：

2.     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

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

本题答案选的是D,但是我选的是A，这里为什么要用be able to 的形式呢？

4.     Child care already a solid part of the employee benefits package at many companies, more businesses are focusing on a newer family benefit known as elder care, servicing for older dependents.

(A) Child care

(B) With child care

(C) Child care as

(D) Being the Child care was

(E) With child care’s being

本题答案选择B,但是我选的是C.能不能帮我解释下呢？

16.   A private house in New York City is a building owned by an individual or individuals having less than eight units and no commercial space.

(A) a building owned by an individual or individuals having less than eight units and no commercial space

(B) one that an individual or individuals own with fewer than eight units and no commercial space

(C) a building with fewer than eight units, no commercial space, and is owned by an individual or individuals

(D) one that has fewer than eight units, no commercial space and it is owned by an individual or individuals

(E) one that has fewer than eight units, is owned by an individual or individuals, and has no commercial space

选项E为正确的，但是不是说过主语一致的时候，重复的谓语可以省略吗？

18.   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 but have remained virtually unchanging

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

E为正确答案，我不是很理解,but前后的时态也不一致，virtually也不知是修饰前面的还是后面的？

20.  20. Puritan fanatics brought to civil and military affairs a coolness of judgment and mutability of purpose that some writers have though inconsistent with their religious zeal, but which was in fact a natural outgrowth of it.

(A) but which was in fact a natural outgrowth of it

(B) but which were in fact a natural outgrowth of it

(C) but which were in fact natural outgrowths of it

(D) but it was in fact a natural outgrowth of them

(E) which was in fact a natural outgrowth of it

答案是E,俺不是太理解为什么？

请各位G友帮忙指点！！不甚感激！

Thanks!

(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 but have remained virtually unchanging

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

E为正确答案，我不是很理解,but前后的时态也不一致，virtually也不知是修饰前面的还是后面的？

20.  20. Puritan fanatics brought to civil and military affairs a coolness of judgment and mutability of purpose that some writers have though inconsistent with their religious zeal, but which was in fact a natural outgrowth of it.

(A) but which was in fact a natural outgrowth of it

(B) but which were in fact a natural outgrowth of it

(C) but which were in fact natural outgrowths of it

(D) but it was in fact a natural outgrowth of them

(E) which was in fact a natural outgrowth of it

答案是E,俺不是太理解为什么？

请各位G友帮忙指点！！不甚感激！

Thanks!