Jake explained that this knowledge is essential to the next phase in 'Earth human' development. . .
杰克解释说，这种知识对于‘地球人类’发展的下一个阶段是必不可少的……If the same decision-making pattern is prevalent outside the United States, sales promotion should prove to be just as indispensable.
如果这种购物方式能在美国以外的其他地方盛行开来，那么，将证明促销活动同样是必不可少的。I used to think it was because we shared the same mother but now I do not believe that to be necessarily true.
我过去常常认为这是因为我们是同一个母亲所生，但是现在我不认为这是一个必不可少的条件了。It has already proved to be vital to entrepreneurs and America's small businesses, which generate up to 80 per cent of new jobs in the US.
事实已经证明，互联网对企业家和美国小型企业是必不可少的，而美国80%的新工作机会来自小型企业。He doesn't retreat into self-pity because of his job as a trashman; instead, he feels proud of it as he thinks it is an essential task.
他并不因为自己是垃圾工而自卑自怜，相反，他很自豪，因为自己正做着一份必不可少的工作。Epidemiology has always been a necessary part of medicine practice.
流行病学一直医学实践必不可少的部分Collagen is an essential and major component of muscles, tendons, cartilage, ligaments, bones, gums, teeth, eyes and blood vessels.
胶原蛋白是构成肌肉，肌腱，软骨，韧带，骨骼，牙龈，牙齿，眼睛和血管的必不可少的重要组成部分。Setting off fireworks and firecrackers seems to have become a hard-to-avoid activity of the annual Spring Festival.
燃放烟花爆竹似乎已成为每年春节期间必不可少的活动。Both intelligence and mechanical dexterity appear to be necessary to make radio transmitting devices for communication between the stars.
看起来智能与机械机敏度这两种能力是制作星际交流的无线传输装置时必不可少的。