18. 降低至：dip to, fall to, decline to, decrease to, drop to, go down to, reduce to, slump to, descend to, sink to, slide to
19. 保持稳定：level out, remain stable, remain still, remain steady, maintain the same level, remain unchanged, stay constant, level off, keep its stability
20. 急剧地：dramatically, drastically, sharply, hugely, enormously, steeply, substantially, considerably, significantly, markedly, surprisingly, strikingly, radically, remarkably, vastly, noticeably
21. 宣称：allege, assert, declare, claim
22. 发生：happen, occur, take place
23. 原因：reason, factor, cause
24. 发展：development, advance, progress
25. 有益的：useful, helpful, beneficial, profitable, rewarding, advantageous,
26. 影响：influence, impact, effect
27. 明显的：clear, obvious, evident, self-evident, manifest, apparent, crystal-clear
28. 占：comprise, take up, account for, constitute, consist of, make up, occupy, hold, compose
29. 对比而言：by contrast, on the other hand, on the contrary, conversely,
30. 展示：show, reveal, illustrate, demonstrate, depict, present, represent, describe
31. 大约：approximately, almost, about, around, nearly, roughly
32. 事实上：practically, in practice, essentially, in essence, in reality, in effect, in fact, as a matter of fact
33. 换言之：namely, that is to say, in other words, to put it like this, to put it differently, to put it from another angle