there has been a d_____in the number of students this year.

There be 句型是就近原则,依此句 much 后修饰不可数名词.但 changes却是复数形式为可数名词,有点矛盾.看much 选 has ,看changes 选have

翻译过来：冬天里有大量雪.选B.因为There be是个句型..没有There have 或has这样的..雪是不可数名词，所以用is.

have,根据 there be 后面的名词判断,后面的名词是复数形式,故用have.

A
There be 结构

Athletic Federa began keeping record ,there has been a steady improvement in how fast ayhletes run, how hight they jump and how far they are able to hurl massive objects, themselves included, through space怎么翻译?
中文翻译:体育联合会开始做记录. 运动员们跑步有多快,他们跳多远,以及根据有限的空间范围能把很沉重的物体能够扔向多远,包括他们自己,在这些方面都已经有了一个很稳步提高/改进.
（1）Althetic Federation ：体育联合会
（2）began keeping record:开始做记录
（3）There has been a steady improvement( 已经有了一个稳步的提高）
（4）in how fast athletes run (在运动员们跑的速度有多快）
（5） how hight they jump and how far they are able to hurl massive objects, themselves included, through space（他们能跳多高以及通过有限的空间范围他们能把很重的物体抛出去多远,包括他们自己在内,）
满意,请立即采纳,谢谢!

没有这种用法.只有用there be才可以.
there has 是不是你在这种句子里看到的呢（纯属猜测）：
There has been an accident.（注：这句话是正确的）
如果你是这么想的,那么让我来告诉你：
上面这个句子是一个现在完成时的句子,尽管它开头用的是"there has",但请你看后面的“been”,所以还是运用了there be 句型.

你的提问很好.
我觉得这不是语法,而是习惯的问题,我网上可以查到不少文献有用 "a considerable debate" 的说法,比如：
"...there has been a considerable debate in contemporary analytic metaphysics in connection with the notion of truthmaker as attempting to capture a basic insight into the way truths depend on reality."
"There have been three kinds of cases,which have generated considerable debates in recent years:indeterminacy,meta-metaphysics,and contextualism/relativism,particularly in connection with practically significant issues regarding gender,race,and sexuality."
上面这两段来自同一篇论文.
如果你谷歌搜索 concern ,你会同样找到
has been considerable concern
has been a considerable concern
的两个说法.
对我来说（英语是我第一语言）,对抽象不可数名词如 concern,anger,consternation,等等,
比如
there has been considerable anger
there has been considerable consternation
个人偏好是 不用 冠词 a ,但这仅是个人看法.