Translation:She smiled happily!
I'm native speaker.
For my feeling, it's because of the rhyme. “笑” is the verb exactly, but when we speak we say "笑了”. It makes the sentence sounds more smooth and more human being. If just say "她高興地笑” sounds like a robot smiles.
You can find some other one-syllable verbs have the same regulations. For example, “哭”, "睡". 他悲傷地哭了 He sadly cries. 他安詳地睡了 He falls asleep peacefully. Here, "了” is just the function words and meaningless, but makes the sentence smooth. If you don't add "了”, we still understand by all means, but it's not the way native speaker's talking.
笑 also means to laugh, but if you want to clarify that she smiled, you want to use the term 微笑
Oh i was just wondering the same thing, is the 了 here really necessary? If so why?
While 了 does mark for completion its also used for many more purposes and functions. In this example it could be taken to mark for completion as well as marking a change of state. Without context its difficult to say for certain
She smiled/laughed happily? (Taking the 了 to imply a completed action and not a continuous one) would this be correct too?
The 地笑 Word Bank tile is silent, they always stay silent for the entire lesson. Defective network code? So sketchy. Reported [The audio does not sound correct] 2019 June 8th Saturday Opera 60.0.3255.141 Mac OS X 10.11.6 64-bit.