In this paper, strong pre-open and strong pre-close sets were introduced in topological spaces and their properties were researched.
在分明拓扑空间中引入强拟开集和强拟闭集的概念，并讨论了它们的性质。
2
Under those circumstances, it is difficult to see how the world economy can return to the pre-crisis levels of growth, or even close to them.
在这种情况下，很难想象全球经济如何能恢复到危机前的增长水平(甚至接近这一水平)。
3
Foreign observers keeping a close eye on Cambodia's upcoming general elections have reported a more peaceful pre-election period than for previous campaigns.