单项选择题

Do you find getting up in the morning so difficult that it’s painful This might be called laziness, but Dr. Kleitman has a new explanation. He has proved that everyone has a daily energy cycle.
During the hours when you labour through your work you may say that you’re "hot". That’s true. The time of day when you feel most energetic is when your cycle of body temperature is at its peak. For some people the peak comes during the forenoon. For others it comes in the afternoon or evening. No one has discovered why this is so, but it leads to such familiar monologues(自言自语) as: "Get up, John! you’ll be late for work again! "The possible explanation to the trouble is that John is at his temperature-and -energy peak in the evening. Much family quarrelling ends when husbands and wives realize what these energy cycles mean, and which cycle each member of the family has.
You can’t change your energy cycle, but you can learn to make your life fit it better. Habit can help, Dr. Kleitman believes. Maybe you’re sleepy in the evening but feel you must stay up late anyway. Counteract (对抗) your cycle to some extent by habitually staying up later than you want to. If your energy is low in the morning but you have an important job to do early in the day, rise before your usual hour. This won’t change your cycle, but you’ll get up steam and work better at your low point.
Get off to a slow start which saves your energy. Get up with a leisurely yawn (呵欠) and stretch. Sit on the edge of the bed a minute before putting your feet on the floor. Avoid the troublesome search for clean clothes by laying them out the night before. Whenever possible, do routine work in the afternoon and save tasks requiring more energy or concentration for your sharper hours.
If a person finds getting up early a problem, most probably ______.

[A] he is a lazy person

B. he refuses to follow his own energy cycle

C. he is not sure when his energy is low

D. he is at his peak in the afternoon or evening
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Which of the following is true about hydrogen [A] Hydrogen is a primary energy source that exists in future. [B] Hydrogen is the second most abundant element in the universe. [C] Hydrogen is like electricity in that it can be used directly. [D] Hydrogen is a kind of energy to be obtained through manufacturing process.
Although it is the most abundant element in the universe, hydrogen is not a primary energy source that exists in nature, as do crude oil and natural gas. Rather, it is an energy carrier ——a secondary form of energy that cannot be found freely in usable form, but has to be manufactured, like electricity. Today, most hydrogen is extracted from fossil fuels. In the future, hydrogen will be made from clean water and clean solar energy.
Hydrogen can match the effectiveness of fossil fuel in powering cars, planes, and ships and in heating homes, schools, and office complexes ——without creating pollution. When burned in an internal-combustion engine, hydrogen emits a virtually harmless water-vapor exhaust. When hydrogen is burned with atmospheric oxygen in an engine, the resulting emission is clean: no unburned hydrocarbons, no carbon monoxide or carbon dioxide.
Hydrogen is an essential component of fuel cells for vehicles and other applications. Fuel-cell engines can be more than twice as efficient as internal-combustion engines, argues Hoffmann. Fuel-cell engines electrochemically combine hydrogen and oxygen in a flameless process that produces heat, electricity, and distilled water. The fact that it is environmentally benign has made hydrogen energy an increasingly attractive alternative to fossil fuels as concerns about resource depletion and global warming have been growing.
"The question is no longer whether we are headed toward hydrogen, but how we should get there, and how long it will take," says Worldwatch Institute research associate Seth Dunn.
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