______ on real ice is very exciting.
I don't know when he . When he , I'll let you know.
—I would like you to talk about the Great Wall.—I’m sorry, but ________ Jack ________ I have been there.
A report on history in our school next month.
Is this the factory __________ you visited the other day?
-----What’s Mary going to do this coming weekend?----- I’m not sure. She ____________ go to the country to see her aunt.