In the question below fill the gap with the appropriate option :
We are _____ to receive your letter and to know that you are _____
Answer Details
The sentence is expressing joy or gratitude about receiving a letter from someone and knowing about their condition. "happy/in good health", and "grateful/sound", both convey a positive emotional response and the indication of the person being in good health. "pleased/all well", is also appropriate in this context, as it expresses happiness and reassurance that everything is good. However, "appreciative/swimming in good health", is not appropriate, as it adds an unnecessary and odd detail about the person swimming. Therefore, the most suitable options for filling the gaps would be either or or depending on the writer's preference for language use.