大大大！ 重大 vs 严重， 广大 vs 大型 vs 巨大
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)