___________ (63)
A.round
B.pitch
C.course
D.court

___________ (65)
A.remaining
B.resting
C.upholding
D.leaving

___________ (66)
A.that
B.which
C.whose
D.what

___________ (68)
A.varying
B.unsteady
C.unsettled
D.altering

What is the main subject of the passage?
A.The effects of cloud seeding
B.The process by which snow crystals form
C.Developments in methods of increasing precipitation
D.The scientific contributions of Vincent Schaefer

After the cloud seeding operations of the late 1940s and the 1950s, the farmers and ranchers mentioned in the first paragraph probably felt
A.optimistic
B.disappointed
C.modest
D.triumphant

Which of the following can be inferred from the passage about the term “weather modification”?
A.It was first used by Vincent Schaefer.
B.It refers to only one type of cloud seeding.
C.It is not as old as the term cloud seeding.
D.It has been in use since at least 1946.

The pronoun “they” refers to
A.ice-forming nuclei
B.water droplets
C.airplanes
D.clouds

When clouds are seeded from the ground, what actually causes ice crystals to form?
A.silver- iodide smoke
B.nuclear radiation
C.dry- ice pellets
D.propane

What does the author imply about the energy problems of the 1970s?
A.They may not be as critical as water problems will be in the future.
B.They took attention away from water problems
C.They were thought to be minor at the time but turned out to be serious.
D.They were caused by a lack of water.