96-1北美

25. The Van de Graaff generator, an electrostatic machine used of nuclear physics to study transformations in subatomic particles, produces powerful electric currents.

这题选B，该怎么改啊？

39. The oriental fruit fly causes extensive damage to grapefruit, lemons, and oranges but does not harm to the trees on which the fruit grows.

这题选B，偶也不明白？

先谢谢了。。。。

25. The Van de Graaff generator, an electrostatic machine used of nuclear physics to study transformations in subatomic particles, produces powerful electric currents.

这题选B，该怎么改啊？

be used in在...方面的运用

39. The oriental fruit fly causes extensive damage to grapefruit, lemons, and oranges but does not harm to the trees on which the fruit grows.

这题选B，偶也不明白？

harm既可以做动词也可以作名词,他们的区别是：

don't harm the trees

do harm to the trees

明显此题中的harm作为名词，那么就应该用形容词no修饰，而不是用副词not来修饰。