下面进行GMAT考试重点试题整理，希望考生充分利用文中所列内容，提高备考效率。
28-3: The primary purpose of the passage is to discuss the
A: techniques used in certain experiments on social learning in birds
B: reasons for the differences between social learning in birds and in mammals
C: question of how social learning manifests itself in birds
D: basis for a widespread belief about a difference in behavior between birds and mammals
E: possible reasons why birds may or may not learn from each other in a particular way
28-4: missing
28-5: According to the passage, which of the following is true of the experiments on domestic hens conducted by Sherwin's research team?
A: Only a small number of observer hens appeared to learn to avoid food that was demonstrated by other hens to be noxious.
B: Observer hens ingested food preferentially only after numerous instances of witnessing demonstrator hens preferentially ingest that type of food.
C: Observer hens appeared unable to recognize when demonstrator hens found a particular food especially palatable.
D: Observer hens appeared unable to recognize when demonstrator hens found a particular food especially palatable.
E: Demonstrator hens altered their behavior less obviously in response to noxious foods than in response to highly palatable foods.
28-6: It can be inferred that the author of the passage would be most likely to agree with which of the following statements regarding the results of the recent experiments conducted by Sherwin's research team?
A: The experiments demonstrate that social learning in avian species facilitates the identification of noxious or toxic foods.
B: The experiments suggest that social learning has made avian species less adept than nonavian species at learning to prefer beneficial foods and avoid noxious and toxic foods.
C: The experiments undermine the notion that most avian species have evolved in environments where there is little benefit to the social learning of unpalatability.
D: The experiments suggest that the acquisition of food preferences in avian species is largely unaffected by social learning.
E: The experiments show that social learning in avian species can promote the preferential consumption of beneficial foods but do not support the claim that social learning in avian species promotes the avoidance of noxious or toxic foods.
以上是对GMAT考试重点试题整理的介绍，希望对考生有所启发，能够加快备考进度，取得GMAT高分。
