更多"The history of life on earth has be"的相关试题:
[单项选择]______ that another earth satellite has been put into orbit.
A. Reporting
B. To be reported
C. To report
D. It is reported
[单项选择]It has been estimated that the earth's surface temperature has increased ______ one quarter to three fourths of a degree since 1850.
A. by
B. at
C. to
D. with
[单项选择]The history of cancer research has shown that
A. miracle cancer drugs often turn up unexpectedly.
B. the mass media can wore wonders.
C. curing cancers in mice is much easier than in humans.
D. animals and humans are similar in behaviour.
[单项选择]First designated in 1970, Earth Day has become an annual international event ______ concerns about environmental issues such as pollution.
A. dedicated to raising
B. dedicated raising
C. dedicated to raise
D. that dedicates to raising
[单项选择]The old couple has been living an _________ life. They have saved up a large sum of money.
A. economy
B. economic
C. economics
D. economical
[单项选择]For three quarters of its span on Earth, life evolved almost ______ as microorganisms.
A. precisely
B. instantly
C. initially
D. exclusively
[单项选择]David likes country life and has decided to______ farming though his father suggests him thinking twice before do it.
A. go in for
B. go back on
C. go through with
D. go along with
[单项选择]
The Earth has a force that pulls thing toward itself. We call this force gravity. This is something we live with all the time, and we take it for granted and hardly ever think about it . But it is a most important factor in rocket operation and must overcome if we are to get anywhere in space, or off the ground at all.
Take the throwing of a ball as an example. The harder the ball is thrown, the faster and higher it will go. What is the secret Its speed. If we could throw the ball hard enough it would go up and up forever and never come down. The speed at which it would have to be thrown do this is known as escape speed. Of course, we cannot throw a ball hard enough because the speed required to escape completely from the Earth's gravity is seven miles per second, or over twenty-five thousand miles per hour.
Once escape speed has been reached by a space
A. runs along the hillside
B. does not need any further power
C. runs freely to all directions
D. does not meet with air resistance
[单项选择]History has demonstrated that countries with different social systems can join hands in meeting the common challenges to human ______ and development.
A. evolution
B. survival
C. satisfaction
D. damage
