Help me,对这段英文改下错,thank you!

题目

Help me,对这段英文改下错,thank you!
However,without the right understanding the promotion of economic,social and cultural factors for the migrant flows,the formulation of policies as the basis for all kinds of restrictions are unlikely to be an effective inspection.At the international level,the need for along-term cooperation strategy in order to achieve common goals,to make immigrants as a positive factor of sustainable development,to prevent the conflict areas between emigrants and local residents;to contribute to positive social and cultural changes.The first half of the 20th century period,international migration has become a major factor for the world's various regions and development of social transformation.With the increase in the number of migration flows and new mobile way,its importance is bound to the 21st century and have to continue inevitably to increase.
是关于中国移民美国的一个总结

答案

However,without the proper understanding of the contributing factors(economic,social and cultural) to the migrant flows as our basis of the formulating of our migrant policies,restrictions are unlikely to be effective.At the international level,there is a need for a long-term cooperative strategy to achieve some common goals.That is to make immigrants as a positive factor of the sustainable economic development; to prevent the conflicts between emigrants and local residents; to contribute to the positive social and cultural changes.In the first half of the 20th century,cross-broader migration was a major factor for the social transformation in many part of the world.With the increase of migration flows and mobility,the importance of migration is bounded to the 21st century and must continue to increase inevitably.
第一句太长,太累赘,可以用中文写过来吗?
最后一句,不太清楚你想说什么