5 . The Japanese Macaca monkey has been studied in the wild for over 50 years. In 1952, on one small Japanese island, scientists dropped some ________ with dirt for the monkeys. The monkeys liked their taste, but they found the dirt ________.
One clever 18-month-old monkey found the way to ________ the problem by washing the sweet potatoes in a nearby river. She taught this to her mother. Her ________ also learned this new way and they taught their mothers too.
All the younger monkeys ________ learned to wash the dirty sweet potatoes to make them ________ to eat. But many older monkeys found it very hard to learn this and still ate the ________ sweet potatoes.
Then something very surprising________. In the autumn of 1958, scientists found that the monkeys on other nearby ________ began washing their sweet potatoes too. Scientists still don’t fully understand how this knowledge was________ from one island to another.
1. A.sweet potatoes | B.green plants | C.hard stones | D.fresh nuts |
2. A.beautiful | B.terrible | C.difficult | D.interesting |
3. A.find | B.reach | C.solve | D.understand |
4. A.children | B.brothers | C.sisters | D.friends |
5. A.quietly | B.easily | C.angrily | D.awfully |
6. A.nicer | B.smaller | C.lighter | D.drier |
7. A.small | B.large | C.new | D.dirty |
8. A.took on | B.took off | C.took place | D.took away |
9. A.trees | B.islands | C.beaches | D.rivers |
10. A.lost | B.dropped | C.passed | D.left |