What are the common greetings when writing to an acquaintance (or someone not necessarily a close friend)? Is "how are you" or "how are you doing these days" too casual in writing ?
Or do I need a greeting before I talk about something else ?
My question is for the English writing exam for Chinese College Entrance Exam. In the past they had the writing exam like these:
Please write to your pen pal Peter in UK, telling him your uncle will be on a business trip to his city, asking some information about his city ...
Please write to an exchange student who stayed in your home last month and had returned to the US, asking his progress in Chinese learning and provides some advice for that.
A friend from UK will visit his Chinese friend next week so he wrote an letter to you asking about the guest etiquette in China. Please writing a response letter.