According to the passage, scientists cannot explain which of the following aspects of squirrel behavior?
A. Where squirrels store their acorn caches
B. Why squirrels prefer acorns over other seeds
C. Why squirrels eat only a portion of each acorn they retrieve
D. Why squirrels prefer acorns from a particular species of oak trees
听力原文:W: Hi, Mark, I didn't know you could paint.
M: Well, I'm just learning. it's for my studio art one of one class.
W: It's pretty good for a beginner.
M: Oh thanks, Judy. The instructor really liked my schedules, but she hasn't seen my painting yet.
W: En, there seems to be something wrong with it though.
M: Yeah, I know what you mean. It doesn't look like to me either.
W: I think I know, look here at the sky, it just seems to filled in with other colors of paining.
M: What do you mean? Everyone knows the sky is blue.
W: Well, that depends. Sometime it is and sometime it isn’t, as sunset can be full of reds and purples. Well, even now, look at now Mark, what do you see?
M: It looks blue to me.
W: Look again. do you see a kind of tallish color?
M: Oh yeah, I see what you mean.
W: By adding some tan to your sky, I think you'll get more actual picture, and the color will look more natural.
M: I think I'll try that. Gee, how do you get to know so much about paining? Have you taken a lot of courses?
W: No, actually. But my father is an artist.
M: A professional artist?
W: Oh yeah. He shows his stophin lots of exhibits, everything is when we were kids; he always talks to us about his work.
M: I wish we could talk some more Judy. How about going for a cup of coffee? I’m ready for a break.
W: I'd love to. but I have to study for a history exam. In fact, I was just on my way to the study group, and I think I am already late. Maybe tomorrow?
M: Great, I'll meet you at the students’ center after my class. a little after three, OK?
W: Sounds good. Get around now.
M: Bye, Judy.
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A study group
B. Studio Art 101
C. The man's painting
D. A professional artist
The author mentions "seeds and fruits" in line 2 as examples of
A. the first crops cultivated by early agricultural societies
B. foods eaten by hunters and gatherers as a secondary food source
C. types of food that hunters and gatherers lacked in their diets
D. the most common foods cultivated by early agricultural societies
A.She's worried that the man will miss next week's deadlineB.She doesn't know when the
A. She's worried that the man will miss next week's deadline
B. She doesn't know when the deadline for tuition payment is
C. The man should have paid his tuition a week ago
D. The man has all week to pay his tuition