23. Lucy is going to have difficulty finding a good job _______ she graduates from a key university.

A．as if

B．even if

C．so that

D．as usual

下列各项中属于人类和环境相对立的生产活动的是(　　)

A．建设“三北”防护林

B．在黄土高原修筑水平梯田，植树种草

C．在洞庭湖周围围湖造田

D．在北京市区内修建多层立交桥