21.We are now living in _____ world where the Internet rules our life, so online searches have become _____ must.
A. the, / B. / , a C. a , a D. a, the
22.—Excuse me. I’d like to book a table for four tonight.
—Sorry, sir, but there is ____ available tonight. You may try another restaurant.
A. no B. none C. nothing D. neither