问题描述：
Mr Smith likes watching his grandson ( A) at the pool.A swim B swims Cswam D to swim 为什么不能选
Mr Smith likes watching his grandson ( A) at the pool.
A swim B swims C swam D to swim
为什么不能选B和C?
grandson是三单,为什么不能加s?
Mr Smith likes watching his grandson ( A) at the pool.
A swim B swims C swam D to swim
为什么不能选B和C?
grandson是三单,为什么不能加s?
问题解答：
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