单选题Mary couldn’t go to 

问题补充：

单选题Marycouldn’tgotothecinemawithusbecauseshehadto_____herlittlebrother.A.look forB.look afterC.look atD.look into

答案：

B解析考查动词短语的区别，look for 寻找、look after 照顾、look at 看、根据句意，故选B.