请英文好的朋友纠正一下我的一句英文翻译：

Question

请英文好的朋友纠正一下我的一句英文翻译：

中文：
在过去，主要的解决方案有海水淡化或建造大坝运河。可是，这两种解决方案都存在着一些问题和不足。

英文：
Major solutions in the past have desalination and the building of dams and canals. However there are many problems and shortcomings in those solutions.

Answer 1

Major solutions in the past were desalination and the building of dams and canals. However, there are some problems and shortcomings in those solutions.
我只是修改了一下语法。

Answer 2

in the past, major two solutions are desalinizing seawater and buiding dams and canals.(或者这里是canal dams依全文而定). However, either has its problems and disadvantages.

Answer 3

Major solutions in the past are desalination and building a dam or canal. But problems and shortcomings exist in both of the solutions.

Answer 4

There are desalination and the building of dams and canals for major solutions in the past. However, both solutions still exist many problems and shortcomings.

Answer 5

Major solutions in the past are desalination and the building of dams and canals.
However, there are many problems and shortcomings for those solutions.