【填句补文】The acid rain(酸雨) is said to be caused by pollution from oil wells in the Gulf of Mexico. Car exhaust gases are also a problem. Local volcanic eruptions make the problem even worse. Nevertheless, with enough money and effort, researchers say that many of the problems could be solved and the rate of erosion reduced. ________.
A
The problem, however, is not just a European one.
B
That is enough to have caused some of the ancient carvings to become seriously damaged already.
C
However, the Mexican government does not have enough money to do the work, and needs to spend what money it has on the Mexican people.
D
Acid rain is how a familiar problem in the industrialized countries in Europe.
