-----------------------------------
必ず, かならず
1. always, without exception, necessarily, certainly, without fail, positively, invariably
必须,必定
-----------------------------------
土砂降り, どしゃ降り, どしゃぶり
1. downpour, pouring rain, heavy rain, pelting rain, cloudburst
倾盆大雨、暴雨、大雨、倾泻的雨、雷阵雨