<p>ok so i recently figured out about the rule regarding "do it" vs "do so"
such as
It is better to quit law school after one semester than to DO SO after four semesters.
Here we have to say 'do so', because we're referring to the action of quitting law school (and there's no NOUN in the sentence that refers to this action). </p>
<p>Students who do the homework at night are just as successful as students who do it in the morning.
In this case, there's a definite NOUN - 'homework' - to serve as the antecedent for 'it'. </p>
<p>but what's the difference between:
1. He could write before the accident, but now he can't.
2. He could write before the accident but now he can't do so.</p>
<p>As to meaning, the two are the same in that either the word “write” or the words “do so” are understood to be there in the first sentence even when left out. Note some purists may argue that a comma is needed before the but in the second sentence.</p>
<p>You initial explanation of the difference is correct and usually one way to figure out which is proper is simply to put in what the do so or do it actually refers to. If it is a verb it is do so, if it is a noun it is do it. For example, in the law school example, the end phrase would become “than to quit” and thus do so is required; in the homework sentence the end phrase becomes “do the homework,” referring to a noun and thus it is do it.</p>
<p>oh ok thanks!
one more question
“His studies in archaeology, led John to propose an idea of a time when dinosaurs were around before mammals.”
Someone gave this as an example on some other forum to show the difference between
“when” and “in which”
They said it should be “led John to propose an idea in which etc”
because idea is the noun, not time. and “idea” is a condition, not a “time”
I agree, BUT this person did not use the word "time’ in their new sentence
What if “when” IS suppoised to modify time? like what if the whole prepositional phrase is “of a time when etc etc”
Basically, say I am unsure of whether to correct “when” or not. How do i know if it is SUPPOSED to be part of the prepositional phrase, or meant to modify the subject?
My guess is that since it is after time, it should be in the prepositional phrase, hence modifying time; hence, “when” is actually correct</p>