Past or Past Participle.

Exercise 4. Change the following sentences to Past or Past
Participle.

1. Frogs suddenly (become) ____________________ extinct.

2. Amphibians as a group have _______________________ (exist) on Earth for over 350 million years.

3. One of the first ___________________ (record) mass extinction of

amphibians, __________ (is) the “golden toad” that _____________
(disappear) from the rain forests of Costa Rica.

4. Now half of the frogs are ______________ (go).

5. The ultraviolet rays come through the ______________________

(damage) ozone layer.

6. Scientist believe that UV rays _________________ (damage)

frog eggs, and juvenile frogs.

7. It is ___________________ (think) that one of the reasons amphibians

__________ (are) more vulnerable to the UV rays _____________

(is) because they __________________ (pass) through one or more
metamorphoses on their ways to adulthood.

8. But it is also true that ultraviolet has ______________ (be)

________ (rule) out in some places where frog extinctions have

_______________ (occur).

9. So scientists ______________ (are) looking at air pollution, water
quality, fertilizer and pesticide as potential causes.

10. At one government test facility in Mary land, scientists _____________

(spray) different types of pesticides on a frog-filled pond to see if

there _______________ (is) an effect.

11. In some cases the animals _____________ (are) born with deformities.

12. The impression I ____________ (take) from this story __________ (is)
that we are racing against time to save the amphibian class.

13. The is so much man doesn’t know, and so much that man has

___________________ (destroy) that the animals are dying.

14. Interior Secretary Bruce Babbitt ___________________ (decide)

to make amphibians a priority issue.

15. They _____________ (are) _______________ (disease),

and malformations _________ (are) occurring, and they are

disappearing out of the planet.

16. At the same time, we ________________ (drink) the water and we

______________ (breathe) that same air that ____________

(kill) them.

17. Scientist have ______________ (begin) to wonder whether the

problem the amphibians ______________ (are) and are having

now doesn’t transcend to other species…including the human race.

18. We have to start to worry if this is something that ____________
(can) raise a human health concern.

19. “They have ______________ (be) here longer than we have,”

20. They have _______________ (survive) for 350 million years, and now
they are being extinct.

Exercise 5. Expansion Activity. Answer the questions orally in
class and then write down the answers for homework.

1. Have you heard of the “amphibians extinction” before?

_______________________________________________________

2. What do you think has really cause the massive extinction?

_______________________________________________________

3. Do you think we can still save the remaining amphibians?

_______________________________________________________

4. In your own words write down how?

_______________________________________________________

_______________________________________________________