题干

1773年,英国科学家普利斯特利做了一个经典实验(如下表),实验得出的结论是(  )

序号

实验材料

处理

实验结果

1

点燃的蜡烛

放到一个密闭的玻璃钟罩里,经过一定时间的光照.

蜡烛熄灭

2

一只小白鼠

小白鼠死去

3

点燃的蜡烛+一盆植物

蜡烛没有熄灭

4

一只小白鼠+一盆植物

小白鼠正常活着

A:植物进行光合作用产生的氧气,提供给了蜡烛燃烧或动物呼吸

B:蜡烛燃烧或动物呼吸都离不开植物产生的氧气

C:蜡烛燃烧或动物呼吸产生的二氧化碳污浊了玻璃钟罩内的空气

D:植物能够更新由于蜡烛燃烧或动物呼吸而变得污浊了的空气

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答案(点此获取答案解析)

D

同类题5

下面文章中有五处需要添加小标题。请从以下选项(A、B、C、D、E 和F)中选出符合各段意思的小标题。选项中有一项是多余选项。

A. Be a Good Listener               B. Care About the Small Acts

C. Begin a Conversation             D. Make Time for Friendships

E. Give a Hand to New Neighbors     F. Remember Their Names

5 Ways To Build Friendship with Your Neighbors

    ①____

    Often neighbors don't even know each other's names. But it's okay to be the one to break the ice. So as you see them at work in their yards, smile, wave and say hello. Ask how their kids are or what they think of the price at the local supermarket.

    ②____

    Your new neighbors may be feeling lonely and unsure, especially if they're far from home. Your help will be welcomed by them. Leave your telephone number to them. If they have any questions, they can call you.

    ③____

    Most of us find it difficult to remember people's names. Writing down the names of your neighbors and note about them, such as "Frank and Jill—Bob's neighbor," helps you remember their names. The next time we see Frank and Jill, we try to call them by name.

    ④____

    If you value a friendship with your neighbors, spend time with them. What better way to meet your neighbors than to invite them to a pool party or holiday open house? Chat with each for five minutes to get an idea of what your neighbors are like so that you can plan for food and music.

    ⑤____

    In a good relationship, it's really the little things that count. Help to bring in the mail for the elderly neighbor when there is a heavy rain. When your neighbor forgets to take in his rubbish cans, roll them back into his yard.