Why was loss of life so massive for Soviets during WW2?

為什么二戰(zhàn)期間蘇聯(lián)人的生命損失如此巨大?

Looking at those charts of WW2 casualties by country (like this one) I always get startled by how massively Soviet casualties outnumber even those of China, even though Japanese military's brutality and cruelty is more infamous than that of Germans.

看看不同國家的二戰(zhàn)傷亡人數(shù)圖表(比如這張),我總是對蘇聯(lián)的傷亡人數(shù)甚至超過中國感到震驚,盡管日本軍隊的殘暴和殘忍比德國人更臭名昭著。