有些在很大程度上依赖旅游业赚取外汇的国家，正在积极努力发展它们的旅游业。

有些在很大程度上依赖旅游业赚取外汇的国家，正在积极努力发展它们的旅游业。
【正确答案】：Some countries depending heavily on tourism for their foreign exchange earnings are making great efforts to develop their tourism.