—1 doubt if he ___________ in the discussion tonight.—I believe if he ____________his homework, he will join us.
—Do you have _______ to say today? —No, nothing.
—What are these? —They’re _______ and _______.
—What were you doing at this time yesterday? —We _______ in the classroom.
—Must we finish the project in a month? —No, you _______.
—Which is _______, the sun, the moon or the earth? —Of course the sun.