⇒ 明天你们不必来了。 Míngtiān nǐmen bùbì lái le. → You don't have to come tomorrow.

why

without fail

⇒ 人们对手机的需求势必会增长。 Rénmen duì shǒujī de xūqiú shìbì huì zēngzhǎng. → People's demand for mobile phones ( 英 ) 或 cell phones ( 美 ) is bound to increase.

surely ⇒ 他必定知道真相。 Tā bìdìng zhīdào zhēnxiàng. → He surely knew the truth.

inevitable

essential ⇒ 开展反腐行动是必要的。 Kāizhǎn fǎnfǔ xíngdòng shì bìyào de. → It's essential that we start a campaign against corruption.

need ⇒ 考试时别忘带上必需的文具用品。 Kǎoshì shí bié wàng dàishàng bìxū de wénjù yòngpǐn. → Don't forget to bring the writing materials you need for the exam.

⇒ 你们必须准时来上班。 Nǐmen bìxū zhǔnshí lái shàngbān. → You must start work on time. ⇒ 记者们必须撤离战区。 Jìzhěmen bìxū chèlí zhànqū. → The journalists have to evacuate the war zone.

presumably ⇒ 他满脸不高兴,想必和老婆吵架了。 Tā mǎnliǎn bù gāoxìng, xiǎngbì hé lǎopo chǎojià le. → He looked totally miserable — presumably he had had an argument with his wife.

not necessarily ⇒ 他未必会接受邀请。 Tā wèibì huì jiēshòu yāoqǐng. → He may not necessarily be able to accept the invitation.

compulsory course

very deferential

be imperative ⇒ 保护知识产权势在必行。 Bǎohù zhīshi chǎnquán shì zài bì xíng. → It is imperative that intellectual properties are protected.

never refuse a request

things go into reverse when pushed to the extreme ⇒ 不要总是批评学生,否则,物极必反。 Bùyào zǒngshì pīpíng xuésheng, fǒuzé, wù jí bì fǎn. → Don't criticize the students all the time or it may backfire on you.