With his attention________on the shops along the roadside，he knocked an old man down while riding to school.

A  concentrating     B．concentrated     C．to concentrate      D．concentrates

答案　B

解析　考查词组，故选B项。

D

解析：考查冠词的用法。第一空为短语：get a +adj+idea of sth.；第二空为特指，特指双方都知道的那个Project plan。