They spent half an hour (pack)their bags 用适当形式填空 过去完成时

They spent half an hour (pack)their bags 用适当形式填空 过去完成时
They spent half an hour (pack)their bags 用适当形式填空 过去完成时

They spent half an hour (pack)their bags 用适当形式填空 过去完成时
packing
spend (in) doing

They spent half an hour packing (pack)their bags
spend .(in) doing sth.