---By the way, how many of us can attend the meeting? ---The number of the students to attend the meeting _____ fifty.

Tony          TV when his mother came in.

--- ________ Tom and his mother often watch tennis matches on TV?--- Yes, they ________.

—I________ you for a long time.  --Oh, I_______ in Beijing. I’ve just come back.

While the boy ______ down the street, the UFO _____ .