It is obvious that many occasions ,from workplace to campus,still need letters
It sounds weird to me, i would say: it is obvious that people still need writing letters on several occasions.
Many universities,for example, are more likely to send handwriting letters to inform students that they are available to their schools
I don think school would send a handwriting letter. They probably send a printed letter.
We can see that the majority of schools regard writing letters as a basic skill of language learning,which means nearly every person in our country is leaning or has acquired how to write letters
has acquired the technique of writing letters.
It only takes people minutes even seconds to receive a message via phones or computers while people will spend days or weeks to see a letter
to receive a letter
In conclusion,as a traditional skill,the technique of letter writing are always needed in official occasions
are --> is
in---> on