1. Can we use "would, could, might" in main clause of 1st type of conditional clause.
Eg: If you study well you u could get high marks"
If so, explain please.
2. What is the main difference between "ON" and "UPON" in terms of keeping something on something. In this condition, how 2 use them correctly.
3. Actually when we should use "OVER" to mean "because of" or "concerning".
We can use could/might to show that even if the first condition is fulfilled, the second is not guaranteed:
If you study, you'll pass- I am certain about the second half if the first condition is met.
If you study, you might/could pass- there's no guarantee of passing if you study, but there is a chance.
There's no real difference in meaning, but 'upon' is less used colloquially.