Adverbs that don't use 地 So I know that to make an adverb, you use 'de/di' and put it before the verb like:


  我兴奋地打开了我的礼物 


But in my studies this week I saw this:


  ...病症的人逐年增加


and


  逐渐成长为独立


Am I right in thinking that these are simply adverbs but to make an adverb from an adjective like 好 or 兴奋 you need a 地？
地 only CHANGES ADJECTIVES to adverb. Any adverbs without being conjugated from adjectives can exist without 地.


地 is commonly omitted. This happens usually when the adjective has ONE CHARACTER only. For example: 慢慢走 or 慢走. 地 is omitted since 慢 has only ONE character. The repetition of 慢 here is only for the purpose of expressing the action in a more visualized or vivid way.
兴奋 has two characters, and you cannot shorten it to one character to have the same meaning, so we usually don't omit 地 in this case.