看得見聽得見的輕快
這一支照著字面走：動作本身透著開心。先是人的動作，再借給會動、會響的東西。
r · B2
In a happy, cheerful way. It describes laughing, singing, talking or waving that clearly shows the person is enjoying themselves, and often makes the people around them feel good too.
開心地；愉快地
核心畫面
One way to hold this word: merrily is brightness you can see or hear in something that is happening. Not a feeling kept inside, but a laugh, a song, a wave, a , a tick. Because it is an adverb, it always hangs on an action, never on a person. Once you have that picture, the other uses are easy to follow. Lend the brightness to a fire or a stream and you get the second use. Lend it to someone who should be worried and is not, and the same word turns into a quiet complaint.
merrily 可以想成「看得見、聽得見的那股輕快」。不是藏在心裡的心情，而是一陣笑聲、一首歌、一個揮手、一聲柴火的…更多收起
merrily 可以想成「看得見、聽得見的那股輕快」。不是藏在心裡的心情，而是一陣笑聲、一首歌、一個揮手、一聲柴火的劈啪、一下時鐘的滴答。它是副詞，所以永遠掛在動作上，不掛在人身上。抓住這個畫面，另外兩個用法就好懂了。把這股輕快借給火或小溪，就是第二個意思。把它借給一個該擔心卻毫不在意的人，同一個字就變成一句不動聲色的抱怨。這只是串起三個意思的一個想法，不必當成每個用法的證據。From the word’s history
The packet's Wiktionary entry gives merry + -ly, from Middle English myriely and Old English myriġlīċe. The -ly ending is what makes it an adverb, and that is why the word always describes how something is done rather than what someone is like.
來源把它記成 merry 加 -ly，再往前接到中古英語的 myriely 和古英語的 myriġlīċe。-ly 這個字尾把形容詞變成副詞，這正好解釋了為什麼 merrily 一直在講「怎麼做」，而不是「這個人是什麼樣子」。
Wiktionary entry for merrily, supplied in this packet (source_ref kaikki:3f6f69a190036ae4:1182317453:8049): From Middle English myriely, from Old English myriġlīċe; equivalent to merry + -ly.
Two branches
照樣開心，卻該擔心
同一個開心的字被放進一個不該開心的場面，落差本身就成了評語。字面沒變，指向卻從心情轉成態度。
r · C1
Doing something in a cheerful, untroubled way while taking no notice of the trouble it may cause. The writer chooses the word to show that someone ought to be worried and is not.
渾然不覺地；照樣（帶著不以為然）