'Should' can be used:
- To express something that is probable. Examples: “John should be here by 2:00 PM.” “He should be bringing Jennifer with him.
- To ask questions. Examples: “Should we turn left at this street?” ...
- To show obligation, give recommendation or even an opinion. Examples: “You should stop eating fast food.”
Where at should be used?
“At” is used when you are at the top, bottom or end of something; at a specific address; at a general location; and at a point. “In” is used in a space, small vehicle, water, neighborhood, city and country.
When should where be used?
Where means in a specific place when used as an adverb or conjunction. A good way to remember the difference is that where has an "h" for "home", and home is a place. Out of the two words, "were" is the most common.
