21. This area experienced______ heaviest rainfall in_______ monyh of May.
A. a; a B. a; the C. the; the D.the; a
22. The college students must study hard to a good knowledge of advanced information technology.
A. take B. catch C. hold D. acquire
23. The Great Wall is so good a place ________ many foreign people come to visit ________ it has become well known all over the world.
A．as；as B．that；that C．as；that D．that；as
