What are the two mysteries that have remained unknown to the modern people?
第4题
A.necessary
B.essential
C.dominant
D.great
第5题
It can be inferred from the last paragraph that scientists ______.
A.are puzzled by the mystery of forest pollution
B.feel relieved by the use of unleaded gasoline
C.still consider lead pollution a problem
D.lack sufficient means to combat lead pollution
第6题
A.who,what
B.what,what
C.what,who
D.who,who
第7题
What will happen if what is proposed by the two scientists becomes true?
A.There will be no need for gasoline substitutes.
B.Air pollution will become a thing of the past.
C.People will be able to use much cheaper energy.
D.There will be no more gasoline-powered vehicles.
第8题
What principles most influenced scientific thought for two thousand years?
A.The speculations of Thales.
B.The forces of electricity, magnetism, land gravity.
C.Aristotle's natural science.
D.Galileo's discoveries.
第9题
What have the two French geophysicists discovered in their research?
A.Some regularity in the changes of the earth's magnetic field.
B.Some causes of the fluctuation of the earth's magnetic field.
C.The origin of the earth's magnetic field.
D.The frequency of polarity reversals.
第10题
A、A couple
B、Colleagues
C、Teacher and student