It took them         time to finish the challenging task.

A．a number of

B．a lot

C．a great deal of

D．a good many

驾驶机动车变更车道时，属于交通陋习的是什么行为？

A．提前开启转向灯

B．仔细观察后变更车道

C．随意并线

D．不得妨碍其他车道正常行驶的车