问题
选择题
Alice was supposed _____ at home, but her mother found her surfing the Internet．
A．studying
B．to be studying
C．to have studied
D．studied
答案
答案：B
考查不定式的形式。Be supposed to do sth应该做某事；本题使用进行时表示不定式动作和谓语动词同时发生。句意：Alice被认为正在家里学习的，但是他的妈妈发现她在上网。本题的be supposed to be doing sth被认为正在做某事。故B正确。