It is not ____ to discuss the question again and again.A.worth B.worthy C.worthwhile D.worth It is not ____ to discuss the question again and again.A.worth B.worthy C.worthwhile D.worth while

1. worth： be worth + n.
当名词为金钱时，表示"…… 值得……"
常见的有 It ’s worth（someone’s）while doing
be worth doing sth. "……某事值得被做"
The question is not worth discussing again and again. 这问题不值得反复讨论。
2. worthy：be worthy of +n. 当名词为抽象名词时表示"……值得……"
be worthy to be done "某事值得被做"
The question is not worthy to be discussed again and again.
3. worthwhile： be worthwhile to do sth "值得做某事"
It is worthwhile to ask him to join the club.值得邀请他加入俱乐部。
4.worth (one’s)while只作表语。worth while 后多接动名词，worth one’s while后多接不定式。
Reading this story is worth while. 读这个故事是很值得的。
由worth的用法可知，此句只适合词组be worthwhile to do sth.。选C。

建议你查一下字典,这三个词的用法,要联系着记.

选A,It's worth to do;It's worthy doing固定搭配

C. worthwhile 值得的（填形容词）

选C it is worthwhile to do 或 doing sth

A. it is not worth to do sth....不值得做。。。
整句意思为 这个问题并不值得讨论来讨论去的。
此空应填形容词 先排除D
而前三项中，worth的意思最符合

选C.
这句话的意思是一再讨论这个问题不值得。句子里有be动词is,那么后面的应该是形容词。
worth和worthy，worthwhile是形容词，而worth while （值得）是动词，所以排除
而 worth 意为equivalent in value to the sum or item specified相当于…价值的，值…钱的
worthy意为deserving effort, attention, or respect有价值的；值得重视的；值得敬重的
worthwhile意为worth the time, money, or effort spent; of value or importance值得花时间（金钱、精力等）的；有价值的
三者对比就不难得出答案了，选C worthwhile