By or Until

'Until' is the correct answer. We use 'until' when a situation (in this example the situation is work) continues up to a certain moment (8 pm). The situation is finished after the moment. In this example, until shows that I was not working after 8 pm.

'By' is the correct answer. We use 'by' when something will happen at or before a certain moment. In this example, we use 'by' to show that you need to return the book before or on December 29th. You cannot return the book after December 29th.

'By' means before or at 9 pm. I will arrive at the party either before or at 9 pm. I will arrive no later than 9 pm.

The correct answer is 'until'. The situation (rain) will continue up to Tuesday. Then the rain stops. With 'until' the situation always stops after the moment (in this example, the moment is Tuesday).

'Until' is the correct answer. The situation (live in Paris) will continue up to April. After April, the situation stops (I stop living in Paris) and I move to Canada.

'By' is the correct answer. You must finish your homework before or on Monday morning.

The correct answer is 'by the time'. It means the same thing as 'by'. Both mean 'before' or 'at'. We use 'by' with specific times of the day, days, months, and years. We use 'by the time' with a verb (in this example: get home)

'By' is the correct answer. 'By' means before. I want to lose five pounds before May.

'By the time' is the correct answer. It means before or at the same time. It has the same meaning as 'by'. We use 'by the time' before a verb (in this example, the verb is arrive).

'Until' is the correct answer. The situation (study at school) continues up to 3:30 pm. After 3:30 pm, the situation (studying) stops.