【填句补文】Mexico's current lack of funds is also partly due to oil. The country has rich oil fields and a few years ago, when oil was expensive, Mexico was selling large quantities of oil to the USA and earning a lot of money. ________. However, the price of oil then dropped, and Mexico has been left owing enormous sums of money and with not enough income from oil sales to pay back the loans.
A
But those ruins are in danger of being seriously damaged by pollution.
B
Scientists estimate that about one millimeter of stone is worn away every twelve years.
C
At others the painted surfaces inside temples are lifting and flaking off and the stone is being eaten away.
D
The government was therefore able to borrow huge sums of money from banks around the world, thinking they would have no problem repaying their debts.
