Many ancient cultures built observatories from which to carry out celestial observations.许多古代文明都有建造天文台观测天象。from which 在这里当什么词性? 若拿到这两个字，对句意有影响吗?Thanks a lot.
A year and half later, my grandfather became gravely ill. When he returned from several weeks in the hospital, he wanted his bed next to the window, where he could see his beloved rosebush.from 加weeks是什么意思？还有in从医院里回来吗？
...them two officials chalked a sign of approval on them. I noticed they were from the Gestapo. They pointed to the two suitcases full of my diaries. through有从空间的一头到另一头的意思，在这的意思是是不是说在箱子里找了个遍，这头到那头都找了。
But officials say there is value in breeding to refine canine traits from human compatibility to bomb-sniffing working dogs. 但一些工作人员表示，培育还是有价值的，可以精进犬类的特性，从易与人类相处到可以排雷的工作犬。【疑问】from to 结构，在...
...前使用定冠词的规律”：https://www.cpsenglish.com/question/62425From a classic
viewpoint, enjoy Lower Falls, the Yellowstone River, and the breathtaking
colors of the canyon (峡谷) while learning about the area’s natural and
human history. Discover why artists and photographers continu...
...有些介词可以后接另一介词短语作宾语，最典型的就是 from under，如from under the tree, from under the bed, from under the table 等，请问 in under 也属于类似用法吗？比如下面这个句子：
Who was the first man to run a mile in under four minutes? 谁第一...
... such as petrol and diesel, combined with lingering concerns over supplies from Russia to propel crude to its highest level in two months.as引导的原因状语从句中increasing prices 是主语，谓语不应该是propel吗？为何用to propel？
...sides of the line when the train left the station in Beijing," Zhang said."Now, there are tall buildings and green spaces. Beijing and Tianjin are more closely connected and the urban environment has also been greatly improved."Fifteen years ago这个时间的立足点是从现在算起，正常下...