A．Two.B．Three.C．Four.D．Not known.How many types of moto……

单项选择题According to the passage, which is the principal energy source of home heat

单项选择题Which of the following countries has the largest share of coal reserves in developing countries

单项选择题According to the Velen model, the middling sort of customers bought luxury goods to______.

单项选择题Which is NOT described as a source of the problems facing the 1970s' Yugoslavia

单项选择题Concerning the answer to who the consumers were, the writer of the passage seems to______.