3.
During a research experiment, a biologist placed a shark into a large tank and then
(1) several small fish into the tank. As you would
(2) , the shark quickly swam around the tank, attacked and ate the smaller fish.
The biologist then
(3) a strong piece of clear glass into the tank, creating two
(4) tanks. She then put the shark on one side of the glass and a new set of fish on the other.
(5) , the shark quickly attacked. This time, however, the shark
(6) because it knocked hard against the glass.
(7) , the shark kept repeating this behavior every few minutes, but
(8) . Meanwhile, the fish swam around
(9) in the other part. Eventually, about an hour into the experiment, the shark
(10) . This experiment was carried out several times. Each time, the shark got less
(11) and made fewer attempts to attack the fish, until eventually the shark got
(12) hitting the glass divider and simply stopped attacking. The biologist then
(13) the fiberglass divider, but the shark didn"t attack. The shark was trained to believe a/an
(14) existed between it and the smaller fish, even when the fish swam
(15) they wished, free from harm.
Many of us, after
(16) setbacks and failures, readily give up and stop trying. Like the shark in the story, we believe that
(17) we were unsuccessful in the past, we will always be unsuccessful.
(18) , we continue to see a barrier in our heads, even when no 4real, barrier exists
(19) where we are and where we want to go, we
(20) see obstacles in our heads.