What is the main idea of the passage?

A. predictable

B. unpredictable

C. changeable

D. unchangeable

A. reduced considerably

B. put a tick

C. examined carefully

D. motivated to develop

A. a kind of harmless animals

B. an achievement of human beings

C. a harmful factor to the environment

D. a kind of useful plants

A. expose foods to sun and wind

B. remove moisture from foods

C. produce pemmican

D. moisten foods

A. chamber

B. flat

C. area

D. studio

A. higher temperature

B. coastal erosion

C. increasing sea level

D. stable rainfall