Question

For many years, ____ animals for carrying food and other supplies from one area to another has been a means of living in Xinjiang Autonomous Region .

A．trained

B．training

C．having trained

D．to have trained

Answer 1

B

试题分析：考查动名词作主语。本题的主语是动名词短语training animals for carrying food and other supplies from one area to another.谓语动词用单数形式。故B正确。C项是完成式，表示已经完成的动作，与句意不符。
点评：动名词做主语指经常性，习惯性的行为。单个的动名词做主语的时候，谓语动词用单数。