GWD 1 -10有句话怎么看不明白~~好心人帮忙来看看

efay

 Low levels of straying are crucial, since the process provides a source of novel genes and a mechanism by which a location can be repopulated should the fish there disappear.

should the fish there disappear,should 这儿是怎么个意思，看不明白阿。

选项D也是 同样个结构,也没看明白

D   an environmentally degraded stream could be recolonized by new salmon populations should the stream recover

D   an environmentally degraded stream could be recolonized by new salmon populations should the stream recover

谢谢好心人啦！

^_^

[此贴子已经被作者于2009-4-21 21:31:21编辑过]

alohabrian

就是虚拟条件句的变体=if the fish there should disappear

efay

谢谢alohabrian ！

了啦~^_^