问题描述：
on nov.18th
Soon they heard the sea.They were carrying the usual rope(绳子),and it was hanging down from the basket of the balloon.At the end of the rope they had tied a metal box.This could hold water,or it could be empty.So they were able to change its weight(重量).It was for use over the sea.They were also carrying some bags of sand.
Soon they heard the sea.They were carrying the usual rope(绳子),and it was hanging down from the basket of the balloon.At the end of the rope they had tied a metal box.This could hold water,or it could be empty.So they were able to change its weight(重量).It was for use over the sea.They were also carrying some bags of sand.
问题解答：
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