We were at the school by now. =We were at the school by present time. We are at the school now. (We are....... now...at the moment) for Example: past...........by now....<<<< NOW(at the moment)>>>>>...............future

"We are at the school now" is correct if you're describing your current location. It would be "We were at the school then/by then" because it is past tense. By now means the act should have been done in the time before now, or will have been done. For example, it's 9am and school starts at 8.45am. The mother says to the children, "Hurry up, you should be at school by now!" (as in you should have arrived before this time). In this sentence you could also use now (as in, you should be sitting in your classroom at this time). The homework is due tomorrow, "You should have started that by now." You can't use now in this sentence, but you could say something like "You've got one night to do it so you'd better start now." My friend left this morning to go on holiday "He'll be at the airport by now". I use by now because I'm not entirely sure but it's what the plan was. If I've just spoken to him on the phone I could say "He's at the airport now" - because he's told me and I know. Another use I can think of is perhaps if you are describing something that has happened to you "I was waiting for the bus and it didn't turn up. Eventually a taxi drove up and by now it was dark so I thought I'd get it..." meaning that it became dark in the time between me starting to wait for the bus and the bus arriving. In this context, "we were at the school by now" could be correct, but "by then" would be more accurate in both cases because it's describing the past. Hope that helps!

We use 'now' when something is in this moment so we must use it with present continuous, or present simple for stative verbs 'We are at school now'. 'By now' is used when you think something should be done before this moment: 'He left our house an hour ago, he should be home by now.' You think something has had sufficient time to be completed. Hope that helps, Andrew

There are a few situations which you should use "by now" in: When something should have happened, but hasn't yet. e.g. We should be at school by now. (Expresses discontent with present situation) We should have been at school by now. (same as above) He should have finished his assignment by now. (Expressing disapproval/concern) When you think something has already happened, but don't know with certainty that it has happened. (expresses a prediction about someone's situation with uncertainty) e.g. (While blindfolded inside a car) We should be at school by now. (When you haven't sighted your friend yet) My friend is probably here by now. When you want to say what would have happened if events had happened differently. e.g. If I hadn't missed my plane, I'd be in America by now. When you want to say that an event is unlikely to occur in future if it has not already happened. e.g. If I haven't tried it by now, chances are I'm never going to try it. There may be other uses but I can't think of them right now. Whereas for "now", it is just used to express the current moment. Your example sentence makes sense with "now" but not "by now". "We are at the school now." makes sense. However, if it is the school you regularly attend, you would not use "the".

We were at the school by now. =We were at the school by present time. We are at the school now. (We are....... now...at the moment) for Example: past...........by now....<<<< NOW(at the moment)>>>>>...............future