434. To sum up, given all the reasons discussed above, we can safely reach the conclusion that the earth is being harmed by human activity.
总之，通过以上讨论的种种原因，我们可以得出这样的结论：地球正在由于人类的活动而遭到破坏。

六级词汇讲解:
本句是建议型的结尾段落。To sum up一般是结尾段的信号词，表示总结，也可以使用In summary、To summarize、In sum、In brief、In short、In a word、In a nutshell、All in all、Generally speaking等表示结论。we can safely reach the conclusion that...后接同位语从句，陈述作者的结论。

句型拓展:
In conclusion, I believe that it's better to be a leader of a group rather than an ordinary member.
总之，我认为做一个团队的领导者要比做普通成员更好。
In summation, I much prefer classes where the students do some of the talking.
总之，我喜欢部分时间由学生发言的上课方式。
My conclusion is that the best way to develop one's skill is to put theoretical knowledge to practical use in the real world.
我的结论是，培养一个人的技能的最佳途径就是将理论知识运用于实践。
I can draw the conclusion that universities should not, and do not need to, spend the same amount on their sports activities as on their libraries.
总之，各高校不应当、也不必在体育设施上投入像图书馆那样多的资金。