Scientists have not yet determined ______.
A: all of the effects of pollution on the human body
B: how pollution can be controlled successfully
C: when the atmosphere first became polluted
D: how to wash the black snow clean
A: all of the effects of pollution on the human body
B: how pollution can be controlled successfully
C: when the atmosphere first became polluted
D: how to wash the black snow clean
举一反三
- Air pollution is becoming worse. As is known to all, air to us is ________ water to fish. No one can imagine how human being can live without air.
- Not until all the fish died ________ how serious the pollution was.
- Not until all the fish died in the river, _______ how serious the pollution was.
- The purpose of this passage is ______. A: to give advice as to how to prevent hearing loss B: to define the effects of noise on human behavior C: to warn people of the danger of noise pollution D: to tell the difference between noise and sound
- Discuss pollution with your child,__________how nice a clean street, lawn, or park looks. A: emphasize B: emphasized C: emphasizing D: emphasizes