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1·It was this that made the organization of irrigation, particularly the building of canals to channel and preserve the water, essential.

正是这点使得灌溉的统筹，特别是建造运河以疏导和保护水，变得至关重要。

2·Since most planetary scientists believe that water is essential to life, the presence of jarosite means that one prerequisite for life was once present on Mars.

由于大多数行星科学家认为水是生命的基本要素，因此黄钾铁矾的存在意味着火星上曾经存在出现生命的先决条件之一。

3·Since the northeast region of North American is interconnected by many streams and waterways, water transportation by vessels like a canoe was most essential.

由于北美东北部地区由许多溪流和水路相连，所以通过像独木舟这样的船只进行水上运输是最重要的。

4·Regulations such as minimum operating age, restricted operating areas and compulsory classes in water safety are essential.

诸如最低操作年龄、限制操作区域和水上安全必修课等规定是必不可少的。

5·The goal of the rovers was to search for and analyze rocks and soils that yield clues to the planet's watery past. Water, of course, is essential for life -at least as we understand it.

它们的目的是寻找并分析火星上的石头和土壤，以寻找这个星球过去是否含水的线索，水当然是产生生命的基本条件，最少是我们理解的。

6·She gives life to all the living things on the earth and provides us with air, food, water and other essential things we need for living.

她给了地球上所有生物生命，给我们提供生活所必需的空气、食物、水和一切基本的需要。

7·In fact, the essential place of water in our diet extends to everyone - whether they want to lose weight, gain weight or stay the same weight!

事实上，水在每个人的日常饮食中的都占有重要地位——无论是他们想减肥，增肥亦或者保持原来的体重！

8·This means provision of the fundamental prerequisites for health: enough food, safe water, shelter, and access to essential health care and medicines.

这意味着提供健康的基本先决条件：足够的食物、安全水、住所、以及获得基本卫生保健和药物。

9·Hope is as essential to your life as air and water.

希望就如空气和水，是人生的必需品。

10·Mars is a six-month flight away, and it has surface gravity, a thin atmosphere, frozen water, carbon dioxide and essential minerals.

飞往火星需要六个月。火星具有表面重力、稀薄的大气、冰冻的水、二氧化碳和基本矿物质。