英语语法达人请进，左边是正确答案，横线上的是我错选的答案，请给出具体原因，以题号为准

Question

D7. The number of registered participants in this year’s marathon was half ____A____.
[A] of last year’s
[B] those of last year’s
[C] of those of last year's
[D] that of last year’s
B8. For there ____D____ successful communication, there must be attentiveness and involvement in the discussion itself by all present.
[A] is
[B] to be
[C] will be
[D] being
A9. There was a very interesting remark in a book by an Englishman that I read recently ___D_____ what he thought was a reason for this American characteristic.
[A] giving
[B] gave
[C] to give
[D] given
C10. No one would have time to read or listen to an account of everything ____D____ going on in the world.
[A] it is
[B] as is
[C] there is
[D] what is

Answer 1

7. 因为that 代表The number of registered participants 。 the number 是单数，如果是复数，用those。A 项是今年的马拉松参赛人数是去年的马拉松一半。显然少了意思，应该是去年马拉松参赛人数的一半。

8，for后面显然不能加整个句子，只能加一个成分。因此只有BD可选。B是指为了某种目的。因此更符合题意。

9 因为句子里不需要谓语成分，且又是englishman 的主动的行为，所以选giving

10。不知道原因。感觉C项不正确。

Answer 2

7.that of last year's= The number of registered participants in last year's marathon 。D项为其的省略。你再看看A选项，是没有这个意思的。
8 是个独立主格结构，相信你也已经看出来了。to be 与being的区别在于前者是“为了。。。”表目的的并且此目的未发生，而being是“作为，是，存在”等已经发生了的，表原因的，二者用法不同，意义也不同。不知我解释清楚没。
9。这个你错的不应该，这就是个主动与被动的问题。giving是主动，given是被动，remark（备注，标记）当然是“主动显示出了”，“给出了”的意思。
10。不会。

Answer 3

B
A
C
A