题干

分类是学习和研究科学的常用方法。对下列纯净物的分类,正确的是

A:碳酸钙和葡萄糖均含有碳元素,都是有机物

B:二氧化碳和臭氧均含有氧元素,都是氧化物

C:氧化铜和高锰酸钾均由不同种元素组成,都是化合物

D:氢氧化钠和碳酸钠溶于水后均能使无色酚酞变红,都是碱

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答案(点此获取答案解析)

C

同类题2

阅读短文,然后在文后表格内完成内容摘要,每空不超过三个词。

    We can remember some important times in our lives. Some things have become good memories. The memories are always in the corner of our mind.

    When I was in a kindergarten(幼儿园), I had many toys and friends. They made me laugh and cry. The teachers taught us many songs and games. We played all day. Although we did not know what learning was at that time, we were learning every day.

    When I was in a primary school, I was excited to learn school subjects. Nearly every subject caught my attention. However, my favorite subject was science. I remembered on the first day our science teacher told us the sun was like a big fire ball. We were quite surprised and kept our mouths open. We began to wonder at the secret of nature. Later many other things came to our ears. We began to learn carefully.

    When I was ten years old, I began to read newspapers, keep a diary, visit museums and make many friends. Every day was something new, interesting and exciting.

    Now I am in the middle school. Each day is new to me. I am still learning happily. It is like a journey to me. I have learned a lot, but there's still a long way for me to go. I hope to become a learned(有学问的) person some day.

Learning is____ a Journey

In a kindergarten

Although we know ____ about learning, we learned a lot

In a primary school

Among all the subjects, I like____ most.

At the age of ____

I began to keep a diary and visit museums.

In the middle school

I hope I won't stop____