作業(yè)精靈老師示例：Last Sunday, Sam and Bobby are playing table tennis happily in the
park.Sam is really good at table tennis. Billy and Willy cheer for them loudly.Sam is too
excited and he hits the ball hard. Then, they cannot find the ball. Finally, Sam and Bobby
see a hole in the ground.Sam has an idea.He brings some water quickly and pours it into
the hole. And they find many balls in the hole.
