must

中文： 应该、必须

1. To do as a requirement; indicates that the sentence subject is required as an imperative or directive to execute the sentence predicate, with failure to do so resulting in a failure or negative consequence. · You must arrive in class on time.· This door handle must be rotated fully.
2. To do with certainty; indicates that the speaker is certain that the subject will have executed the predicate. · If it has rained all day, it must be very wet outside.· Where would you have put the keyring? You couldn’t have lost it again! - I must have, because it's nowhere to be found.
3. Used to indicate that something is very likely, probable, or certain to be true. · The children must be asleep by now.· There's the doorbell. It must be Dad.

复数 must · He/she/it must · 过去式 must