請英語高手們幫我區別一下下面的兩題~感激不盡啦~

題目：

請英語高手們幫我區別一下下面的兩題~感激不盡啦~
1.Beijing sold 154200 new cars in the first half of 2011,___ is 224200 fewer than the same period in 2010.
A.what B.that C.whose D.which A
2.Accepting the award on the stage was an amazing moment,__ he would never forget.
A.which B.what C.one D.it
第一題爲什麼不選which呢？第二題爲什麼不選which呢？既然第一題選了what,那麼第二題爲什麼不能選what或者是which呢？

解答：

其實,第一題會不會是答案錯了呢.
個人覺得選D which
就是典型的非限制性定語從句,which指代前面說到的所賣出的汽車數量,比2010年同時期的要少了224200.
網上搜了一下,看到有新聞的原文（連結發不上,直接弄過來）
>Car sales drop in Beijing
北京半年少賣22萬輛車
Beijing sold 154,200 new cars in the first half of 2011,which is 224,200 fewer than the same period in 2010 and shows a 59.2% year-on-year decrease,according to data released Thursday by China Association of Automobile Manufacturers and Beijing Yayuncun Car Trade Market,the Beijing Times reported.The trade volume of 2nd-hand cars hit 122,600 in the first 6 months of 2011,which dropped by 46% from the same period in 2010.Beijing’s policy on limiting the purchases of cars and the adjustment on personal income tax threshold exclude 90% of non-permanent residents in Beijing from the group of potential car buyers.
據《京華時報》報導,中汽協、亞運村汽車交易市場等14日聯合發布數據顯示,今年上半年,北京市累計交易新車154200輛,比去年同期少賣了224200輛,同比降幅達59.2%；二手車累計成交122600輛,同比減少了46%.限購新政及個稅起征點調整將使90%的外地在京人員無緣在京購車.
2.這裡的one是同位語 一般 one= a/ an +n.
這題目的 one= an amazing moment
Accepting the award on the stage was an amazing moment,one that/ which he would never forget.=Accepting the award on the stage was an amazing moment,one he would never forget.
上台領獎是一個讓人激動的時刻,一個他將永遠都難忘的時刻.
one 是同位語,表示的是「這個時刻」,後面再加了個定語從句來修飾這個時刻,「他將永遠難忘的時刻」.因爲在定語從句中,one充當的是賓語,所以引導詞which/that可以省略掉,變成了題目中的Accepting the award on the stage was an amazing moment,one he would never forget.
which 個人覺得,從語法上來說也是行的,但是當表示非限制性定語從句時,這題目的which容易引起歧義,可以是表示這個moment,可以是表示上台領獎這件事情,而用同位語one,它表示的是moment的同位語,因此就很明確是說這個moment,是最佳的答案.
再問： 嗯嗯~那麼這樣說來，可不可以理解爲第一題的which既可以指代前面的一整個句子，也可指154200這個數字，爲了避免歧義，就用what來代指154200，並且引導這個句子呢？