A
句意:戴安娜过去开车上班,但现在她习惯走路,因为路上拥挤,而且她想保持健康。
used to do sth. 过去常常做某事
be used to doing sth.习惯于做某事
第一空,表示过去常常做的事,用used to do sth. 过去常常做某事
根据because the road is crowded and she wants to keep fit.但现在她习惯走路了,因为路上拥挤,她想保持健康。
可知她现在习惯了步行上班。
用be used to doing sth.习惯于做某事
故本题选A