问题补充：
—Where is Jack?
—He basketball on the playground.
A. plays
B. is playing
C. is going to play
D. play
答案：
A. plays
(答案→)B. is playing
C. is going to play
D. play
解析：句意：.—杰克在哪里？—他正在操场上打篮球。A. plays一般现在时，主语是第三人称单数时；B. is playing现在进行时；C. is going to play一般将来时；D. play一般现在时。故选B。
考点: 考查动词时态的用法。
