Apart from the majority of countries, the U. K. has ______ to form the whole part of its constitution.

单项选择题Why should governments ensure the careful handling and recycling of the CFCs now in use

单项选择题The best way to save ozone is ______.

单项选择题At first, locomotives could not popularize themselves because they ______.

单项选择题In a true sense, plateways are the earliest and most primitive railways invented by ______.

单项选择题The multi-tube boiler system made the Rocket, Robert’s locomotive, ______.