责任感和可靠性是必需的素质，友善和外向的性格也必不可少。
Responsibility and reliability are necessary qualifications, as well as a friendly and outgoing personality.
很不幸，在日常生活中疼痛虽然令人很不悦但却是必不可少的。疼痛会警告人们那些可能会伤害到自己的事物来保护他们。 （根据原文的意思疼痛是生活的必需品的而不是避免的，也就是说疼痛本来是对人有很多好处的，你的翻译意思上有点不对。）
PAIN, unfortunately, is a horrible necessity of life. It protects people by alerting them to things that might injure them.
Control -flag：这指定任何特定模块是必不可少的、必需的、可选的还是足够的，从而定义模块的行为。
Control-flag: This defines the behavior of stacking modules by specifying whether any particular module is requisite, required, optional, or sufficient.
硒又是人体必需的重要微量元素之一，同样也是其他动、植物新陈代谢必不可少的生命元素。
It is also the necessities of body and one of the most important microelement, and the indispensable life element of the metabolism of a ll creatures.
一系列全面的营养包括必不可少的维生素和矿物质，全面的食物，和精确比率的必需脂肪酸EPA和DHA。
The broad nutritional profile includes essential vitamins and minerals, whole foods, and precise ratios of essential fatty acids EPA and DHA.
农产品作为人们生活的必需品，在人们的日常生活中必不可少，与此同时，农产品已经成为国民经济持续稳定增长的保障。
Not only they are the necessity of the life, but also are the promotion of the continued growing of national economy.
超市在本人们生活中势必不可少的，本人们在超市里购物，取得必要的生活必需品。
Supermarket potential in our lives are essential, we are in the supermarket shopping, access to essential necessities of life.
超市在本人们生活中势必不可少的，本人们在超市里购物，取得必要的生活必需品。
Supermarket potential in our lives are essential, we are in the supermarket shopping, access to essential necessities of life.
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