Examples
nǐ你bì xū必须zài在hòu tiān后天yǐ qián以前wán chéng完成huí jiā回家zuò yè作业。
你必须在后天以前完成回家作业。
You must get this homework finished by the day after tomorrow.
你完成你的工作了吗？
Have you finished your work?
你必须在中午以前完成这个工作。
You have to get this work finished by noon.