1. There is a need for the conservation of trees, or there will soon be no forests.
    有必要保护树木，否则不久将会没有森林了。

2. Conservation is one way to make sure we have enough energy in the future.
    对自然资源的保护是保证我们将来有足够的能源的一种办法。

3. However, conservation alone is not the answer.
    然而，仅仅靠节约还不是解决问题的办法。

1. 守恒：守恒(conservation):即使物体的外表发生了变化,但如果不增加或拿去什么,物体的物理性质不会改变. 可逆性是指儿童理解了物理活动和心理操作都是可逆的. 形式运算阶段(11岁~):儿童发展出了抽象推理和假设思维的能力 思维变得抽象了,

2. 保留概念：他们的学习虽以直觉感知为主, 但已渐渐摆脱了以自我为中心的思维, 能注意更多事物不同方面的线索, 通过具体事物来引起记忆、想象、判断与推理, 并且逐渐对保留概念( conservation) 以及对互补、可逆、同一性等特性也有所了解,

1. (对环境的)保护
    Conservation is saving and protecting the environment.

    e.g. ...a four-nation regional meeting on elephant conservation.
           四国保护大象的地区性会议
    e.g. ...tree-planting and other conservation projects.
           植树以及其他环保计划

2. (对文物或艺术品的) 保护
    Conservation is saving and protecting historical objects or works of art such as paintings, sculptures, or buildings.

    e.g. Then he began his most famous work, the conservation and rebinding of the Book of Kells...
           之后他就开始了他最为出名的工作，即保护并重新装订《凯尔斯书》。

3. 节约;防止浪费
    The conservation of a supply of something is the careful use of it so that it lasts for a long time.

    e.g. ...projects aimed at promoting energy conservation.
           旨在促进节约能源的计划
    e.g. ...rules concerning the conservation of fishery resources.
           有关保护渔业资源的规定

1. the preservation and careful management of the environment and of natural resources

2. (physics) the maintenance of a certain quantities unchanged during chemical reactions or physical transformations

3. an occurrence of improvement by virtue of preventing loss or injury or other change

    Synonym: preservation