急~这句英语有语法问题吗？

Question

They suggest that trees and plants that grew in the UK before towns and cities were built should be allowed to grow again.
这句英语的时态使用有没有错，如有错请说明为什么？

Answer 1

They主语 suggest谓语 that trees and plants that grew in the UK before towns and cities were built should be allowed to grow again宾语从句.
宾语从句：that引导词 trees and plants主语 that grew in the UK before towns and cities were built定语从句 should be allowed谓语 to grow again主语补语
定语从句that关系代词引导词（主语） grew谓 in the UK状 before towns and cities were built状语从句
这句话的时态没有错误。grew用过去完成时也行，但因为有before或after，也可以不用过去完成时。如：
He (had) arrived here before we left.

Answer 2

grew应该改为 had grown
suggest后面引导宾语从句，而trees and xxx后面引导定语从句，before是一个非常重要的提示词，before意思是在……之前，before后面引导从句用的一般过去时，而在过去的过去用过去完成时，所以要改成had grown，之后便没有语法错误了，因为suggest翻译成建议引导宾语从句，从句用should+动词原形，且should可以省略的虚拟语气

Answer 3

没看出大问题。
那个grew发生在过去的过去，可用完成时，但grew本身有成长的意思，不一定完成，也就是一直在grow,所以这里不用过去完成时是可以的。
这是一个有多个从句组成的复合句，包括宾语从句，定语从句，状语从句。
该句第1个that引导了一个宾语从句；
该句第2个that引导了一个定语从句，修饰宾语从句的主语（trees and plants），而该定语从句自身又带了一个状语从句：
that grew in the UK before towns and cities were built
这里before towns and cities were built 是时间状语从句，修饰定语从句that grew in the UK发生的时间。
该句缩句形式如下：
They suggest that trees and plants should be allowed to grow again.
供参考

Answer 4

没有什么问题，你的翻译是什么