液化石油气主要成分是丙烷、丙烯、丁烷、丁烯。（）
参考答案：对
Many countries are increasing their use of natural gas, wind and other forms of ________.[ ]
A. power
B. force
C. energy
D. strength
油品丧失流动状态时的温度，亦即油品在试管里倾斜45℃经过5～10s尚不流动时的温度称为( )。
A．燃点 B．闪点 C．露点 D．疑点
untries are increasing their use of natural gas, wind and other forms of ________.[ ]