—That's right. What's worse, the price of oil has increased ________ 60 percent.
A:of; to
B:of; by
C:from; by
D:for; on
Have you seen _______ at the foot of the hill?
①自然资源是人类赖以生存的物质基础
②大自然是人类赖以生存的基础,我们必须做它的奴隶
③资源短缺等问题是我国特有的现象
④人口、资源、环境等一系列问题,已经直接威胁到我们和子孙后代的生存