11.I have seen trees,__c___ open at sunrise and close at sun

11.I have seen trees,__c___ open at sunrise and close at sunset.
A.which the leaves B.of which the leaves C.whose leaves D.its leaves
那C可以的话B为什么不行?
16.Is the river __B___ through the town very long?
A.flows B.that flows C.which flow D.the one flows
同样 B可以 C为什么不行?
31.Put the letter ____c__ he can find it easily.
A.in which B.at which C.where D.which
C可以的话A也应该可以啊?
53.Is it that museum ____A____ they’d like to visit during their trip to Japan?
A.that B.which C.where D.as
同样,为什么B不可以选呢?
这几道题目是我从网上下载的课件,对照答案后,我感觉似乎是答案出错了?

I have seen trees, __c___ open at sunrise and close at sunset.
A. which the leaves B. of which the leaves C. whose leaves D. its leaves
答案是C,那C可以的话B为什么不行?
这几道题目是我从网上下载的课件,对照答案后,我感觉似乎是答案出错了?请各位朋友帮帮忙
答：答案没错,是出题有误.
其实这题作为非限制性定语从句来造句是不妥的.I have seen trees.一句的意思是不完整的,后面一定要加上一个限制性的定语（从句）才意思完整：我见过叶子日出日落闭的树.
如果没有这个逗号,确实是用C较好：I have seen trees whose leaves open at sunrise and close at sunset.
但用B也是正确的：I have seen trees of which the leaves open at sunrise and close at sun set.
还有一种方式是：the leaves of which., 这种结构多用于非限制性定语从句,用在这里,两个名词紧挨在一起,感觉不是很好：I have seen trees the leaves of which open at sunrise and close at sunset.
这题可能出题者疏忽了,B项本来应改是：of which leaves, 这样答案就是唯一的了.
16题问不在关系代词上,而在从句的主谓一致上.
31题：put sth.+somewhere , 这个somewhere是副词性的,可以是介词短语,也可以是副词性从句.这里只有where能引导副词词从句,而in/at which都是用来引导定语从句的.
53. Is it that museum ____A____ they’d like to visit during their trip to Japan?
A. that B. which C. where D. as
为什么B不可以选呢?
答：这题出得比较好.
译：他们很想在去日本旅行期间参观的就是那家博物馆.
析：限制性定语从句的先行词前不用指示代词this ,that,而用the,尽管翻译成汉语时有“.的那个、这个.”的意思.因为指示代词就是用手指着说的.而限制性定语从句是不用手指,而用一个与从不同特征让人明白讲的是何物,何人,何事.
如本题将这个that改为the,则会产生歧义和争议.
如改为the museum, 则ABC都通,AB时,后为限制性定语从句,就有上文指出it是什么.如：Look at the building. It is the musuem (that/which).
选C为强调句型已经说过了.