---Tom, it’s 10.00 p.m. now. It’s time for bed. ----OK. ___________.Mum.
—I hear Tom is leaving.— ____________ why?
—Huang Wei rides a bike very well. Who taught him? —No one. He taught _________.
— What a heavy rain! Will it last long? — ______ . We are getting into the raining season now.
— We finished counting all the birds, Miss Zhang. — ______ ! Boys and girls, let’s have a rest.
“The children are playing in the park.”The main structure of the sentence is ______ .