It's well-known that rice is the ______ food of more than half the world's population.
A.soft
B.staple
C.stable
D.steady
- · 有4位网友选择 D,占比50%
- · 有3位网友选择 A,占比37.5%
- · 有1位网友选择 C,占比12.5%
A.soft
B.staple
C.stable
D.steady
It is a wellknown fact that ______ (国家的发展取决于年轻一代的素质).
The more fundamental and far-reaching a scientific theory is, the more speculative it is likely to be. It is erroneous to believe that science is only concerned with "pure facts", for mere accumulation of facts is a primitive form. of science. A mature science tries to arrange facts in significant patterns to see relationships between previously unrelated aspects 'of the universe.
A theory that does not suggest new ways of looking at the universe is not likely to make an important contribution to the development of science. However it is also important that theories are checked by new experiments and observations.
Dr. Ovenden discusses recent discoveries in biology, chemistry, and 'physics that give clues to the possibility of life in the solar system and other star systems. He discusses conditions on Mars, Venus, Jupiter, and Saturn, and considers whether or not the same conditions may be found on planets of other stars.
Only the planets Venus, Earth, and Mars lie within the temperature zone, about 75,000, 000 miles wide in which life can exist. Venus is covered by a dense layer of clouds which permit no observation of the surface, and the surface temperature of the planet is not known.
Mars is colder than Earth, the average temperature being about minus 40 degrees Fahrenheit, compared with plus 59 degrees Fahrenheit as the average for earth. However near the Mars poles during the summer season, temperatures may rise to as much as 70 degrees Fahrenheit, whereas winter temperatures may fall to minus 130 degrees Fahrenheit.
Because of the extreme difference in the Martian(火星的) seasons, the only life forms expected to exist, without a built-in(内在的,固有的) temperature control such as warm-blooded animals and humans have, are those which would stay inactive most of the year.
Attempts have been made to detect in the spectrum of the dark markings on Mars, the absorption lines due to chlorophyII. So far the test has not succeeded. But the infrared spectrum of the Martian markings has been found to be very similar to the spectrum of earth vegetation when studied at high altitudes.
Life, as we know it, most likely would exist on Mars near its ______.
A.poles
B.equator
C.center
D.canals
What can we learn about Fight-it? 查看材料
A.It helps the diabetics in financial difficulties.
B.It organizes parties for volunteers once a year.
C.It offers less expensive medicines to diabetics.
D.It owns a wellknown medical website.
How much is the rotational inertia I of a uniform thin disk (mass m, radius R), if the axis is along the line of its diameter?
A uniform solid cone (mass M, radius R, height h) rotates about its symmetric axis, its rotational inertia will be
A、
B、
C、
D、
A.Lowering its prices.
B.Selling more household necessities.
C.Changing its membership rules.
D.Opening up more checkout lines.
In general, the more liquid an asset the______.
A.less it is likely to yield
B.greater its risk of default
C.lower its market price will be
D.more it will add to bank profits
An analog signal m(t) with zero mean is a stationary process. Its frequency range is 0(Hz) ~ 8000(Hz) and its amplitude is uniformly distributed between -5(V) ~ +5(V). Then, the minimum Nyquist sampling frequency for this signal m(t) is f (Hz) , the average power is P (W). Assuming a uniform quantizer for this signal and the step size is D=0.04(V), the minimum number of quantization bits is R .
A、f=8000, P=25, R=8
B、f=16000, P=25/2, R=7
C、f=8000, P=25/3, R=9
D、f=16000, P=25/3, R=8
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