precipitously
adv. 陡峭地；出乎意料地；陡然地
同义词
参考例子
1.The mountain path descended precipitously to a small valley.
这条山间小道急转直下通到一个小山谷。
2.That was primarily motivated by a fear that mail would decline precipitously and they needed a new source of income.
这样，首先就会产生一种邮件数量会大大减少的恐惧，进而，他们会需要一个新的利润增长点。
3.After all, it is those areas that are closest to the melting point that can tip precipitously—as did Arctic Ocean sea ice in recent years.
毕竟，正是这些地区最接近融点，而一旦到达融点就有可能突然倾覆，象近年来北冰洋的海冰一样。
英文解释
adv.
1.very suddenly and to a great degree
2.abruptly; in a precipitous manner
网络释义
precipitously
险峻;