COMPREHENSION Based on the reading, write T for true or F for false. 1.
Scientists have begun to study risk taking in animals because they are more interesting than humans.
2.
Lee Dugatkin has studied risk-taking behavior in birds.
3.
Research has shown that teenagers take more risks if they are with friends.
THINK ABOUT IT Discuss the questions with a partner or in a small group. 1. H ow did you answer the question about swimming toward a bigger island in the first paragraph of the reading? Why did you make this choice? 2. Do you believe that animal research can help explain human behavior? Why or why not?
2.1 The Present Perfect — Form SUBJECT
HAVE/HAS (+ NOT)
PAST PARTICIPLE
I
have
taken
some risks.
EXPLANATION
You
have not
seen
the photographs.
We
have
read
about risk taking.
Scientists
have
studied
risk in animals.
There
have
been
interesting experiments.
He
has not
researched
humans.
There
has
been
a new study.
Use have with the subjects I, you, we, they, or there + a plural subject.
Use has with the subjects he, she, it, or there + a singular subject.
Notes: 1. The contraction for have not is haven’t. The contraction for has not is hasn’t. I haven’t taken a lot of risks in my life. Dugatkin hasn’t studied rats. 2. We can contract the subject pronoun with have or has: I’ve, you’ve, we’ve, they’ve, he’s, she’s, it’s. I’ve read about animal behavior. She’s never taken many risks. The apostrophe s (’s) can mean has or is. The verb form following the contraction will tell you what the contraction means. He’s studied human behavior. = He has studied human behavior. He’s studying human behavior. = He is studying human behavior. 3. We often contract singular nouns with has, especially when speaking. The researcher’s won many awards. This article’s been downloaded by a lot of students. 4. We can contract there + has. There's been a study of teenage risk taking. continued
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