问题
选择题
A driver should ________ the road when _________.
A．concentrate on; drive
B．concentrate in; driving
C．concentrate to; drove
D．concentrate on; driving
答案
答案：D
考查短语及非谓语动词。concentrate on集中，句中逻辑主语driver，与drive之间为主动关系，故用现在分词，选D。