constructive

形容词 constructive:

1. constructing or tending to construct or improve or promote development
2. emphasizing what is laudable or hopeful or to the good

1. I can not figure out why they ridicule this constructive suggestion.
   我弄不懂他们为什麽嘲笑这一建设性建议。
2. It was regrettable that such great issues had to be the thrust and parry of a general election. But at least the debate should be constructive.
   如此重大的问题不得不成为大选中人们激烈辩论的议题，这很令人遗憾。可这场辩论至少应该是建设性的。

con.struc.tive

adj.（形容词）
Serving to improve or advance; helpful:
建设性的：起改进或提高作用的；有帮助的：
例句：
constructive criticism.
建设性的批评

Of or relating to construction; structural.
结构的：构筑的或与构筑有关的；结构上的
Law Based on an interpretation; not directly expressed.
【法律】 指定的：在解释的基础上的；未直接表达的

【引伸】
construc.tively
adv.（副词）
construc.tiveness
n.（名词）