题目内容：

During an experiment, a biologist put a shark into a large tank and then put several small fish into it, too.

As you would_____, the shark quickly swam around the tank（容器）. When it found the smaller fish, it _____ began to attack and eat them. The biologist then placed a strong piece of _____ glass into the tank, creating two separate parts. She then put the shark in one part of the tank and a new group of fish in _____.

Again, the shark quickly attacked. This time, however, the shark knocked into _____ glass divider and bounced off(弹回). The shark kept repeating this behavior every few minutes but it _____. Meanwhile, the small fish swam around _____ in the other part. About an hour later, the shark_____ up. This experiment was repeated several _____ over the next few weeks. Each time, the shark got less aggressive(攻击性) and didn’t want to ______ attacking the small fish, until the shark got ______ of hitting the glass divider and simply stopped attacking.

The biologist then removed the glass divider, ______ the shark didn’t attack. The shark was trained to believe there was a barrier(障碍) between itself and the small fish, so the fish swam wherever they wished, without ______.

In fact, many of us, after experiencing setbacks and failures, emotionally give up and stop trying. Like the ______ in the story, we believe that because we were unsuccessful in the past, we will always be unsuccessful. In other words, we continue to see a barrier in our heads, even when there is no “real” barrier ______ where we are and where we want to go.

1.A. worry    B. fear    C. expect    D. remember

2.A. heavily    B. quickly    C. carefully    D. busily

3.A. dirty    B. dark    C. light    D. clear

4.A. another    B. other    C. the other    D. others

5.A. a    B. an    C. the    D. (不填)

6.A. wanted    B. failed    C. left    D. hit

7.A. happily    B. quietly    C. safely    D. politely

8.A. took    B. gave    C. put    D. cut

9.A. minutes    B. months    C. groups    D. times

10.A. allow    B. stop    C. forget    D. try

11.A. tired    B. excited    C. used    D. surprised

12.A. and    B. so    C. or    D. but

13.A. death    B. danger    C. interest    D. hope

14.A. shark    B. fish    C. glass    D. tank

15.A. among    B. from    C. through    D. between