如果x=54y，那么x和y成______比例；如果xy=5，那么x和y成______比例．

Passage Three

Countries sometimes spoil their beauty spots because ______.

A．they are too poor to build beautiful hotels on them

B．they have to cut down trees to build hotels on them

C．they have to sell them to borrow money from foreign banks

D．they are lacking experience in building hotels