单项选择题
A．By selling services that make life comfortable. B．By selling land containing oil. C．By selling public lands. D．By selling coal and other natural products.
A．He was not happy with the new director. B．He was not qualified to be an engineer. C．He wanted to travel. D．He found his job boring.
A．It can be cooked in many ways. B．It is delicious but inexpensive. C．It gives higher yields than other grain crops. D．It grows easily in various conditions.