题干

梓潼同学长期以来的早餐搭配:一碗稀饭、一根油条和少量泡菜.回答下列问题:

(1)梓潼的早餐食谱中缺乏人体需要的____ 和维生素等营养素,长期如此,容易导致营养不良.建议他增加进食____ 和少量蔬菜、水果等.

(2)新鲜的蔬菜和水果中含有丰富的维生素C,可预防____ .(填疾病的名称)

(3)梓潼想探究番茄和柑橘中维生素C含量的高低,他查阅资料得知,维生素C溶液能使一定量的紫色高锰酸钾溶液褪色,并且维生素C溶液越浓,褪色程度越明显.

【提出问题】柑橘中维生素C含量比番茄中的高吗?

【作出假设】柑橘比番茄味道酸,柑橘中的维生素C含量比番茄中的高.

【实验步骤】

①如图,向两支洁净试管中各加入2ml一定浓度的紫色高锰酸钾溶液,编号为甲、乙两组;

②再同时向甲、乙两支试管中分别加入1ml柑橘榨汁、1ml番茄榨汁,振荡摇匀;

③一段时间后观察两支试管现象.

【实验结果与结论】

____ ,说明假设成立;若乙试管中颜色褪色比甲试管中明显,或两支试管中____ ,说明假设不成立.

【实验分析与评价】

本实验中甲组与乙组形成____ 关系.为了使实验更严谨、更科学,张磊同学建议可再加丙组实验:向丙组试管中加入____ ,振荡摇匀.

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答案(点此获取答案解析)

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同类题1

先通读下面的短文,然后根据短文内容,在空格内填入一个最适当的词,所填单词必须在答卷标有题号的横线。每空只能填一字

What is a hurricane?(飓风)

    You may already know that hurricanes are storms that can cause devastating(毁灭性的) waves, wind, and rain. They happen during “Hurricane Season,'' from June 1st until November 30th in the Atlantic Ocean and from May 15th until November 30th in the Pacific Ocean.

Categories(类别)of Hurricanes

    There are five categories of hurricanes, which are based on wind speeds. The categories help people know how much damage(危害) a hurricane may cause because the greater the wind speed, the more dangerous the storm. For example, a Category 5 hurricane has winds over 155 miles per hour, which are strong enough to break the buildings along the seaside completely.

Hurricane Dangers

    When a hurricane happens together with heavy rainfall(降雨), there can be a devastating flood. The centre of a hurricane is called the eye. While most of a hurricane has dangerously strong winds, the eye in fact is a calm area in the storm. When the eye of a hurricane passes over land, people might think that it's over, but before long the wind and rain increase(增长) again as the second part of the hurricane moves through.

Hurricane Safety Tips

    There is no way to stop a hurricane or make it change direction, so if you ever find yourself in the path of a hurricane, be sure to stay inside during the storm. You could be seriously injured(受伤) if you go outside.

Hurricanes


Characteristics

Devastating waves, wind, and rain are usually the ____ of hurricanes.

Categories

Hurricanes are ____ into five categories by scientists, based on wind speeds.

 ____ 

The eye is the ____ of a hurricane. Soon after it passes, the wind and rain increase again.

Safety Tips

It's ____ to stop a hurricane or change its direction..

Stay inside during the storm, or you could be seriously injured.