(B)to have
(C) they have
(D)are having
10．The province of Alberta lies along three of the major North American flyways
Used by birds _______between their winter and summer homes.
(A)the migration
(B)migrating
(C)migrate
(D)and migrate
11．Astronomers estimate ______called the Pleiades in the constellation Taurus is 415 light-years away from Earth.
(A)that a loose cluster of stars
(B)a loose cluster of stars is
(C)that is a loose cluster of stars
(D)there is a loose cluster of stars
12．Pearl Sydenstricker Buck, _____ the Nobel Prize for Literature in 1938, is Best known for her novels about China.
(A)won
(B)winner of
(C)to win
(D)who the winner of
13．Stage producers Klaw and Erlanger were the first to eliminate arguments among leading performers _______in order of appearance, instead of prominence.
(A)of whom list the program
(B)the program listing
(C) for them the program listed
(D)by listing them on the program
14．During the decades after the United States Civil War, a host of technical advances made possible ______and uniformity of railroad service.
(A) a new integration
(B)for a new integration
(C)that a new integration
(D) and a new integration
15．Forests stabilize _____and retain precipitation, thereby helping to prevent erosion and regulate the flow of streams.