单选题Jack does his homework&nb

问题补充：

单选题Jackdoeshishomework________Mary.Sotheybothalwaysgetgoodgradesintheexams.A.so careful asB.as carefully asC.so carefully asD.as careful as

答案：

B解析as···as之间加adv或adj，本题修饰动词，故选副词的原级，故选B