Since the start of the space age, more and more littering has occurred in orbits near Earth, often because the intentional discarding of lens caps, packing material, fuel tanks, and payload covers.

(A) more and more littering has occurred in orbits near Earth, often because

(B) orbits near Earth have become more and more littered, often from

(C) orbits near Earth became littered more and more, often resulting from

(D) there have been more and more littering of orbits near Earth, often because of

(E) there had been littering more and more of orbits near Earth, often with

OA is B

请问 B里面的 often from到底是谁的modifier? 我找不到可以被他修饰的Noun啊.

如果 说often from是做adverbial modifier，它修饰的动词是哪一个？ 这算是那一种结构have become...., from...?

B里面的often from就是做状语修饰become的

文章愿意是这样的： 从空间时代之初开始，距离地球很近的环绕物变得越来越垃圾了，通常（这些环绕物的垃圾化）来自于丢弃的空间望远镜、包装材料、燃料箱以及装载材料的包装。

这里整个from 短语实际上修饰了become 表示一个伴随过程 即空间环绕物是如何变得越来越垃圾的

这种介词短语作为状语的例子是很常见的。

from…介词短语作方式状语

Do you speak from experience?

你是就经验而谈吗？

from修饰littered么...从什么什么中丢弃出来

litter这里是动词“乱丢垃圾”的意思