These words all describe sb/sth that is extremely important and completely necessary because a particular situation or activity depends on them.以上各词均表示极其重要、完全必要、必不可少。
essentialextremely important and completely necessary, because without it sth cannot exist, be made or be successful指极其重要的、完全必要的、必不可少的：◆Experience is essential for this job.对于这个工作，经验是非常重要的。
vitalessential指极其重要的、完全必要的、必不可少的：◆The police play a vital role in our society.警察在我们的社会中起着极其重要的作用。
essential or vital?用 essential 还是 vital？
These words have the same meaning but there can be a slight difference in tone. Essential is used to state a fact or opinion with authority. Vital is often used when there is some anxiety felt about sth, or a need to persuade sb that a fact or opinion is true, right or important. Vital is less often used in negative statements.以上两词意义相同，但语气稍有区别。essential 用以说明事实或表明权威意见，vital 常用于对某事感到急迫或需要使人信服某一事实或意见确实、正确或重要等情况。vital 较少用于否定句：◆It was vital to show that he was not afraid.最重要的是要表现出他毫无畏惧。◆Money is not vital to happiness.
crucialextremely important because a particular situation or activity depends on it指至关重要的、关键的：◆It is crucial that we get this right.我们把这个问题弄明白是极其重要的。
criticalextremely important because a particular situation or activity depends on it指至关重要的、关键的：◆Your decision is critical to our future.你的决定对我们的将来至关重要。
crucial or critical?用 crucial 还是 critical？
These words have the same meaning but there can be a slight difference in context. Critical is often used in technical matters of business or science; crucial is often used to talk about matters that may cause anxiety or other emotions.以上两词意义相同，但使用场合稍有区别。critical 常用于商业或科学的技术问题，crucial 常用于可能引起焦虑或其他情感方面的问题。
decisiveof the greatest importance in affecting the final result of a particular situation指决定性的、关键的：◆She has played a decisive role in the peace negotiations.她在和谈中起了关键作用。
indispensableessential; too important to be without指必需的、不可或缺的：◆Cars have become an indispensable part of our lives.汽车已成了我们生活中必不可少的一部分。
Patterns
essential/vital/crucial/critical/decisive/indispensable for sth
essential/vital/crucial/critical/indispensable to sth
◆This case emphasizes / highlights the importance of honest communication between managers and employees.这个事例凸显出经理与员工之间坦诚交流的重要性。
◆Effective communication skills are essential / crucial / vital.有效的交流技巧是至关重要的。
◆It should be noted that this study considers only verbal communication. Non-verbal communication is not dealt with here.应该注意的是本研究只考查了言语交流，在此没有涉及非言语交流。
◆It is important to remember that / An important point to remember is that non-verbal communication plays a key role in getting your message across.非言语交流在传递信息过程中起着重要的作用，记住这一点非常重要。
◆Communication is not only about the words you use but also your body language and, especially / above all, the effectiveness with which you listen.交流不仅涉及使用的词语，同时也涉及身体语言，尤其与能否有效听取对方的话有关。
◆I would like to draw attention to the role of listening in effective communication.我想让大家注意倾听在有效交流中扮演的角色。
◆Choose your words carefully: in particular, avoid confusing and ambiguous language.注意用词，特别是避免使用令人费解和有歧义的语言。
◆Finally, and perhaps most importantly, you must learn to listen as well as to speak.最后，也许是最重要的，你不仅要学会说还要学会听。
➡ note atessential➡language bank atvital[only before noun]connectedwithornecessaryforstayingalive生命的；维持生命所必需的◆thevitalorgans(= thebrain, heart, lungs, etc.)重要脏器(ofaperson人) fullofenergyandenthusiasm生气勃勃的；充满生机的；热情洋溢的SYNdynamic