21. My grandfather has sent me _____ e-dog as my birthday present.
A. a B. an C. / D. the
22. --Which would you like, a cup of tea or a glass of milk?
-- ______. I think I'll just have a glass of water.
A. Both B. Neither C. None D. Either
23. –Which do you think is ____ important, air tank, space suit or digital camera for an astronaut?
--I think the digital camera.
A. less B. the most C. more D. the least