16.Those interested in covered bridges can find six of they between Keene and

A B C D

Winchester,New Hampshire.

17.The Sun's energy is generated deep in the solar core by the synthesis of helium

A B C

from hydrogen through a sequences of thermonuclear fusion reactions.

D

18.Using carbon-dating techniques,archaeologists can determine the age of manyA

ancient objects by measurement the amount of radioactive carbon they contain.

B C D

19.The evolutionary adaptation of a particular species of animal over time occurs in

A B

response to environmental conditions,including others animals.

C D

20.Saturn is the second largest planet after Jupiter,with a diameter nearly ten times

A B C

those of Earth.

D