Question

The environment here has been greatly improved in recent years．    trees are thick and

 green，birds remain all the year long．

 A．Even if       B．Although          C．Unless            D．Where

Answer 1

D

解析:

本句考察复合句。句意为：近几年这里的环境有很大的改善，树又密又绿，鸟儿一年四季都在这里。用where作为引导词，整个从句来说明这里的环境的确是改善了。