—What are the birds doing ? —They are in the tree.A.sing B.singing C.sings
The train arrives ____ Beijing . A in B. at C. to
_____people are buying tickets. A.Many B. Much C. How many
There______ three boys in the classroom. A. is B.are C. have
_______ everyone happy? A. Am B.Is C. Are
Who _____ tired? A.am B. is C. are