问题
选择题
石油是一种没有固定沸点的油状物,经过汽化、冷凝分离后可得到汽油、煤油等产品。由此可以判定石油属于
A.氧化物
B.纯净物
C.化合物
D.混合物
答案
答案:D
题目分析:石油中含有汽油、煤油等多种成分,属于混合物。选D。
点评:混合物是由不同种物质组成的,成分复杂;而纯净物是由一种物质组成的,成分单一。
石油是一种没有固定沸点的油状物,经过汽化、冷凝分离后可得到汽油、煤油等产品。由此可以判定石油属于
A.氧化物
B.纯净物
C.化合物
D.混合物
答案:D
题目分析:石油中含有汽油、煤油等多种成分,属于混合物。选D。
点评:混合物是由不同种物质组成的,成分复杂;而纯净物是由一种物质组成的,成分单一。
完形填空。 | ||||
Music as medicine. Do you like turning 1 the radio to your favorite music to drive 2 away. Many people do use music for themselves, for example for relaxation to 3 their moods. But the study of music therapy (疗法) takes the use of music much further, from combating cancer. The uses of music therapy are great. Music therapy can 4 reduce (减轻) the anxiety of hospital 5 undergoing difficult medical procedures. Difficulty 6 is a common problem for cancer. Music therapy which helps promote deep breathing, lower heart rate, lower 7 pressure. That can help cancer patients sleep 8 Relaxing the body can also help reduce physical pain, and people may need less 9 People don't have to be 10 to respond to music. It's relaxing, comforting and soothing. | ||||
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