填空题
It is an ___________ which may be brown, green or black in color.
填空题
The word "petroleum" comes from ___________ and ___________.
填空题
Petroleum that comes directly from deep in the ground is called___________
填空题
At a refinery the crude oil is ___________ into its various parts.
填空题
From the refined oil we obtain important products, such as___________, kerosene, detergents, ___________, and perfumes.