Questions 66-70         According to scientists, frogs are disappearing from the earth. Since 1997,the frog population has dropped (66) 2 percent every year. Some frogs specieshave completely (67) . No one can be sure why this is happening, but a numberof scientists are looking into it. Joe Pechmann, a professor at the University ofNew Orleans, has been studying frogs for 18 years. He believes there are severalstresses on our planet that are killing off frogs. These problems (68) pollution,global warming and loss of the frog habitat due to human population growth.Pechmann warns the loss of frogs should be taken seriously. “It makes sense intheory that what happens to frogs will happen to us,” he said. Even if we are not at(69) , we may have to take (70) for the extinction of frog species that havemanaged to survive for millions of years before man.
【題組】66.
(A) at
(B) for
(C) by