21.Stay a bit longer, please. It’s been such _____fun having you here.
--- Thank you, but I’ve got _____ early start tomorrow morning.
A. /; a B. a; an C. /; an D. the; an
22. －I don’t think I can walk any further.
－______. Let’s stop here for a rest.
A. Neither I can B. Neither can I C. I don’t think so D. I think so
