1.
_____ a necessary dimension for measuring astronomical space and the distance of heavenly bodies form the Earth.
2.
Jackie Joyner-Kersee, _____ the world record in the heptathlon in the 1988 Olympics, also won the long jump in the year.
3.
The fossilized remains of a type of camel _____ a dog have been found in the Bad Lands of South.
4.
Gorillas are quiet animals, _____ they are capable of making about 20 different sounds.
5.
Although the Earth's chemical composition had been studied for years, only toward the end of the nineteenth century _____ as a discipline in its own right.
6.
Because the wood of the dogwood tree is very hard, _____ is used for objects, such as roller skate wheels, in which hardness is desired.
7.
In hot, dry regions, the Sun's heat causes the outer layer of rocks _____, a process called exfoliation.
8.
The lower _____ in a room, the more slowly our eyes focus.
9.
_____ Sarah Orne Jewett, a nineteenth-century writer, read widely in her family's extensive library.
10.
In the early twentieth century, the "Model T" automobile was mass-produced and sold at a price _____ could afford.
11.
Not only _____ all the positive charge of an atom, it is also the site of the weight of every atom.
12.
The wind-rippled sand at California's Kelso Dunes resembles _____.
13.
Fossil records indicate _____ existing in the past have become extinct.
14.
Experiments related to the sense of smell are more easily _____ than those related to perception of color.
15.
The Pulitzer Prize has been _____ in American literature for more than seventy years.
