There are about five million species in the oceans and we have yet to learn much about them. Life in the oceans ranges from the tiniest plankton all the way up to giants like sharks and whales. What makes the ocean such a great place to live? The answer is water.
The chemical structure of water makes it an excellent medium for life. Water is actually quite simple, but the Way the water molecule is formed gives water its unique properties. The water molecule is made up of two hydrogen atoms and one oxygen atom. They form a polar molecule, that is, one with a slightly positive end and a slightly negative end. Because water is polar, it can break down both solids and gases.
When dissolved gases and solids mix with pure water, the result is sea water, or salt water. The salinity of the earth’s oceans is about thirty-five parts per thousand, meaning that there are about thirty-five grammes of dissolved solids and gases in one kilogramme of water.
Density is the relationship between mass and volume and is measured in kilogrammes per cubic metre (kg/m3). The density of pure water is 1,000 kg/m3, meaning that one cubic metre of water weighs one thousand kilogrammes. If a substance has a higher density, say 5,000 kg/m3, it will not float on water. Marine animals and plants take advantage of the density of water.
Heat capacity is the amount of energy it takes to raise the temperature of a substance by one degree centigrade. The heat capacity of water is relatively high. Water can absorb and give off a lot of heat without big changes in temperature, thus creating a stable environment.
文中共有10处语言错误,错误涉及一个单词的增加、删除或修改。 注意:1.每处错误及修改均仅限一词; 2 只允许修改10处,多者(从第11处起)不计分。 Dear James, I’d like to tell you anything about our sports meeting. It was holding on Oct.10th, that was a fine day. Over 2,000 students and teachers attend it. Yu Le, a student from my class won the 100-meter race. He finishes the race in 12.6 seconds and broke in the school record. The sports meeting was really success. That was because we were all trying to do my best. Although I was not one of the winner, I was proud of what we had done. I am looking forward to receive your letter. Yours, Li Hua
Recently a program called “Learning to Respect Our Parents” is started in our school.
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Learning to Respect Our Parents Recently a program called “learning to respect our parents” is started in our school. As we all know, respecting parents is one of China’s traditional moral value. However, as most students today are the only children in the family, they often regard themselves as the center of the family, not caring much for their parents, for the program, ten dos’ have been worked out for the students to follow. For example, we are advised to remember our parents’ birthdays and express our good wishes to them. When leaving home, we should tell our parents what we will do. Besides, we are supposed to greet our parents when they return home. The program has been very successful and has won a lot of praise from parents and other members of society.