My selected Keywords for reading 1

audience
A group of people who come to watch and listen to someone speaking or performing in public

sedentary
spending a lot of time sitting down, and not moving or exercising very much

nutritional
relating to the substances in food that helps you to stay healthy

What i have comprehended from the reading 1:

In the reading 1, there are 4 short texts which have been written for different audiences. We are asked to recognize the type of each short text as magazine/newspaper, academic journal, advertisement, and online encyclopaedia according to their corresponding audiences.
It seems the first one, A, be an online encyclopaedia. Beacuase it provides a summary information about "Physical Activities". The second short text uses more formal language. It discusses about the results of a study which has been done on the sedentary lifestyles. So, it is related to a journal paper. The short text C, uses informal and simple sentence structures, and has been written for a general audience. So, it should be a piece of a magazine or newspaper. Finally, the last one introduces an advanced home sport equipment, called Leapfrog, and enumerates its special features. Therefore, it is an advertisement.