A．He likes students with high motivation．
B．He enjoys teaching intelligent students．
C．He tailors his teaching to students' needs．
D．He treats all his students in a fair manner．
A．It is mostly imported from the Middle East．
B．It is a sure indicator of its economic activity．
C．It has a direct impact on the international oil market．
D．It equals more than 30 million barrels of oil each day．
A．It eventually turns into heat．
B．It is used in a variety of forms．
C．Its use is chiefly responsible for air pollution．
D．Part of it is lost in the process of transmission．