Should - Assumptions

Point 1: We use should to express things that we expect to be true or come true.

1. The bus usually arrives at this time.
2. The bus should be here any minute.
3. This medicine helps relieve pain.
4. This medicine should help you.
5. The weather is usually nice this time of year.
6. The weather should be nice tomorrow.

Point 2: We use should not to express things that we do not expect to be true or come true.

1. It is does not cost much money.
2. It shouldn’t cost much money.
3. It does not take a long time to do.
4. It shouldn’t take long to do.
5. The shop is supposed to be open.
6. The shop shouldn’t be closed.

Point 3: We use should not in questions when we think something is not common or correct.

1. You think a chair is misplaced.
2. Shouldn't the chair be over here?
3. You think the bus should be here.
4. Shouldn't it be here by now?
5. You thought the shop would be open.
6. Shouldn’t the shop be open?

Point 4: When answering a question, we answer Yes and No differently.

Shouldn't the bus be here by now?

1. Yes, it should.
2. No, it is always late. (no + reason)

Shouldn't you be in bed?

1. Yes, I should, but I can't sleep.
2. No, I need to be awake. (no + reason)