大大大！ 重大 vs 严重， 广大 vs 大型 vs 巨大 So, having had a look into the HSK5 vocab which involves the character 大, I have come across a few instances where I am not sure what is used in which circumstance. 


重大 vs 严重 - these both mean important/critical in an objective sense (rather than 重要, which is subjective). But, when you choose 重大 over 严重? You seem to be able to say 重大事件 and 严重事件 - does anyone know what the difference between these two critical situations is? I think you would call 911 in both circumstances, right?
广大 vs 大型 vs 巨大 - these all mean 'massive/humongous'.  There likewise doesn't seem to be much difference between them. Maybe 广大 is more related to surface area (horizontal) while 大型 and 巨大 are more vertical in scope? Not sure...


Any input would be much appreciated!

Hashamyim
重大 = huge; important
Example: 重大发现 (huge/important discovery),  重大发明 (huge/important invention) . You cannot say 严重发现 or 严重发明

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严重 = serious; seriously
Example: 严重罪行 (serious crime) 严重缺乏 (seriously lack). You can also say 重大罪行 (huge crime) but not 重大缺乏 (both are adjective). Meanwhile 重大缺点(huge fault) is valid because 重大 is an adjective and 缺点 is a noun

广大 = &quot;vast&quot; (area) e.g. 广大区域 (vast area)
大型 = &quot;big/ large&quot; (scale/ size) e.g. 大型机器(big/ large machine) , 大型计划 (big/ large plan)
巨大 = &quot;huge&quot; (size) e.g. 巨大发现 (huge discovery), 巨大发展 (huge development)