Answer:
a) It is not the case that the dress is yellow
a) The dress is multicolored
b) Mary has been exercising
step-by-step explanation:
The saying negates that the dress is yellow and saying the dress is multicolored implies that the dress is not just one color or just yellow.
For part b, the condition is, is Mary wearing tennis shoes. The conclusion then is that Mary has been exercising because she is wearing tennis shoes.