the students in this school is about four thousand,      of them are boys．

A．A number of, three fifth

B．The number of, three fifths

C．A number of, three fifths

D．The number of, three fifth

机翼油箱中各有几个电动泵？

A、机翼油箱中各有两个电动泵

B、没有电动泵，因为油箱是空气增压

C、机翼油箱中各有一个电动泵

D、所有油箱中总共有两个电动泵