Question

Since then the number of people taking driving lessons ____20.

A．has increased to

B．increases by

C．has increased by

D．have increased by

Answer 1

C

试题分析：句意：自那时以来考驾驶课程人的数目已经以20%的速度增加。since then自从那时起，用于现在完成时；by表示比率作“以…为单位”解时,常与表示单位的名词或数词连用，表示增加或减少了，to增加到；the number of做主语，谓语用单数形式。increases是一般现在时的形式。故选C。
考点: 考查动词的用法。