(i) if a1, a2, . am are each countable sets, then the union theorem 1.5.8. a1 u a2 uam is countable. (ii) if a is a countable set for each n e n, then uan is countable.

The denmark sound is a busy but water way

Use your vocabulary words to complete the sentences below. more of the world's population is now concentrated in heavily populated urban areas known as a this is quite a contrast from the past when or native groups were either farmers or — hunters and gatherers who moved between places in search of food. advanced technology has led to the integration of world economics and cultures, in the world's more developed countries. this integration requires , the responsible use and management of natural resources.

What processes does carbon cycle through the biosphere?