21. This is ______ most interesting story and I plan to read it ______ second time.
A. a; a B. a; the C. the; the D. the; a
22. Twenty students want to attend the class that aims to teach______ to read fast.
A. what B. how C. who D. why
23. The children are full of ______. They have been playing all day long without resting.
A. force B. power C. energy D. strength
