Answer:

If you ___ explain why you are so late?
- Should: If you should explain why you are so late, it implies that it is necessary or expected for you to provide a reason for your lateness. This is a polite way to inquire about the reason behind the delay.
- Must: If you must explain why you are so late, it signifies a strong obligation or requirement for you to give an explanation for your tardiness. This is a more forceful way of requesting a justification for being late.
- Ought to: If you ought to explain why you are so late, it suggests a moral or societal expectation for you to clarify the reason for your lateness. It is a subtle way of indicating that providing an explanation is the right thing to do.
- Could: If you could explain why you are so late, it indicates that you have the ability or option to provide a reason for your lateness. It leaves room for you to decide whether or not to give an explanation.
- Might: If you might explain why you are so late, it suggests a possibility or likelihood that you will offer a reason for your tardiness. It implies uncertainty or indecision on your part.
- Can: If you can explain why you are so late, it signifies that you have the capability or permission to provide a justification for your lateness. It emphasizes your ability to offer an explanation.
- Need not: If you need not explain why you are so late, it indicates that you are not required or obligated to give a reason for your tardiness. This gives you the option to choose whether or not to provide an explanation.
- Would: If you would explain why you are so late, it suggests a willingness or intention on your part to offer a reason for your lateness. It indicates a polite and courteous attitude towards explaining the delay.