单项选择题
A left-luggage office is a place where bags（）be left for a short time，especially at a railway station.
A.shouldB.canC.mustD.will
单项选择题 After two years' research, we now have a（）better understanding of the disease.
单项选择题 It’s based on the idea（）all people are created equal，（）is accepted by most people.
单项选择题 Barack Obama，（）African America，was elected as（）56th President of the United states.
