Which of the following is an example of the third form of cooperation as it is defined in the passage?
A.Students form a study group so that all of them can improve their grades.
B.A new business attempts to take customers away from an established company.
C.Two rival political parties temporarily work together to defeat a third party.
D.Members of a farming community share work and the food that they grow.

Which of the following statements about primary cooperation is supported by information in passage?
A.It was confined to prehistoric times.
B.It is usually the first stage of cooperation achieved by a group of individuals attempting to cooperate.
C.It is an ideal that can never be achieved.
D.It is most commonly seen among people who have not yet developed reading and writing skills.

According to the passage, why do people join groups that practice secondary cooperation?
A.To associate with people who have similar backgrounds.
B.To get rewards themselves.
C.To defeat a common enemy.
D.To experience the satisfaction of cooperation.

The word “cherished” in paragraph 1 is closest in meaning to __________ .
A.agreed on
B.prized
C.set up
D.defined

It can be inferred from the passage that research concerning the distress signals of trees _________ .
A.is no longer sponsored by the government
B.has been unproductive up to now
C.was conducted many years ago
D.is continuing

Which of the following could be considered a cause of the distress signals of trees?
A.lack of water
B.attacks by insects
C.experiments by scientists
D.torn roots

It can be inferred from the passage that the sounds produced by the trees ________ .
A.are the same no matter what type of tree produces them
B.cannot be heard by the unaided human ear
C.fall into the 1-20 kilohertz
D.serve as a form of communication among trees

The word “them” in line 3 refers to _________ .
A.scientists
B.trees
C.vultures
D.insects

____________ (53)
A.finish
B.end
C.edge
D.stop

____________ (51)
A.knowledgeable
B.recognizable
C.ware
D.intelligent