John's salary
as a bus driver was much higher than that of a teacher.这个句子在比较前后分别使用了两种不同的所有格，这样用也可以吗？是不是应该改成：John’s salary
as a bus driver was much higher than a teacher's.
...上看到一句话 it's easy to make friends you are rich,but a friend in need is a friend indeed.it's easy to make friends you are rich是什么结构，you are rich是定语吗？定语不是只能修饰名词么，看它在这句话里不像是修饰friends的，但是定语可以修饰整句...
Throughout our history, immigrants have contributed to American society and help build the American dream
请问:可以将help改成helping吗？答案改成helped将其看作与contributed并列。那可以理解成and后面省略了have contributed to，helping…做它的宾语吗？
On the other hand, scientists disagree about how much and when they
should share data, and they debate whether sharing it is more likely to
accelerate science and make it more robust, or to introduce vulnerabilities and
problems.whether sharing it is more likely to ... 为什么这里有个it，起...
Several schools are within easy reach. 几所学校都在附近不远处。 He lives within easy distance of his work. 他住在离上班很近的地方。 以上两句分别用了 within easy reach 和 within easy distance，好像意思差不多，它们有区别吗？
it was a storage jar made of earthenware, no doubt discarded because a break had made it useless.这句中连接词是什么？是which is的省略吗？定语从句中可以省略which is的所有情况，以及非限定中可不可以省略which is？