重要，必要，主导，关键，根本，意义重大：

　　essential

　　e.g. Libraries are an essential part of this process, providing the only access for those who do not have the resources to purchase or access books and information on their own. 图书馆是在这个过程中一个必不可少地部分为那些靠自己无法获得资源或者接触书籍和信息的人，提供了唯一的途径。

　　vital

　　e.g. It is vital to your mind, soul, body and your life on the whole that you stay in the present with all your thoughts and feelings. 总得来说,认识到自己所有的想法和感受都存在于现在,这对你的心理、灵魂、身体和你生命是非常重要的。

　　influential

　　e.g. In the US one of the most influential and lucrative professions is law, a field in which writing skills are indispensable.

　　在美国最有影响力收入也最高的职业之一就是律师，而这一行中写作技能是绝对必要的。

　　overwhelming

　　e.g. He developed an overwhelming desire to exert power—to dominate, control and possess another person. 他发展出了压倒性的权力欲望——去支配、控制和占有另一个人。

　　fundamental

　　e.g. This decision represents the fundamental interests of the people. 这个决定反映了广大人民的根本利益。

　　indispensable

　　e.g. United Nations is an indispensable organization, but an organization that can only work because of the staff and their contribution and your dedication. 联合国是一个必不可少的组织，但也是一个全因有了其全体职员的贡献及他们的奉献才能运作的组织。