根据要求改写句子。
1.He spent 10 yuan buying the pen . (改为同义句)
He ___10 yuan __ the pen.
2.Finishing the work is hard . (改为同义句)
_hard _ the work.
3.Why not go shopping ?(改为同义句)
_ shopping ?
4.If you aren't quick , you'll miss the bus . (改为同义句)
_, __ you'll miss the bus .
