schemes是什么意思？

Smith has written a breezy guidebook, with a series of short chapters dedicated to specific aspects of urbanity - parks, say, or the various schemes that have been put forward over the years for building the perfect city.

A tax on upstream carbon sources is one easy way to put a price on carbon emissions, although some countries may wish to use other methods, such as emissions trading schemes.

But that won't stop inventors from dreaming up new ways to fly and trying to persuade investors to back their sometimes outrageous schemes.