He looks so sad,we think he may be u_______

He looks so sad,we think he may be u_______ He looks sad because there are so many problems ___________. Mr Black:_____ _____John?He looks so sad. He looks very young,so he ____ be a student. He looks so unhappy that he seems to _____ the sad news. He looks so cool. A：_____ _____ John?He looks so sad.B:Because his dog's leg h he looks tired these days.Yes,i think so.you know he works() yes,he looks so young. what does he look like?回答he looks sad He must be ill,｛｝he looks so pale.A.since B.because C.as D.f i think he may be in the classroom. No , he () be there. i s