11¡¢Revolutionary developments in both observational and theoretical astronomy (took place) in the 1960¡¯s.

A.commenced

B.occurred

C.were disputed

D.were exchanged

12¡¢In the legends of the American West, Paul Bunyan¡¯s most (treasured) possession was Babe the Blue Us, whose horns were said to span a distance of 42 ax handles.

A.comical

B.valued

C.expensive

D.colorful

13¡¢A supernova is a star that explodes and then slowly fades to less than its original (brightness).

A.size

B.weight

C.radiance

D.imortance

14¡¢Over six million citizens of the United States collect benefits from (private) pension plans each year.

A.unauthorized

B.confidential

C.nontransferable

D.nonª²governmental

15¡¢Since the 1950¡¯s literary critics have attempted to answer the question: When did children¡¯s literature first (emerge) as a distinct literary genre?

A.improve as
B.appear as

C.conform to

D.respond to