An enormous number of people in the world"s poorest countries do not have clean water or adequate sanitation______.

单项选择题Today investigators are still far from______a master map of the vasculature of the heart.

A．constituting
B．decoding
C．drafting
D．encoding

单项选择题We now obtain more than two-thirds of our protein from animal sources, while our grandparents ______only one-half from animal sources.

A．originated
B．digested
C．deprived
D．derived