The bags and suitcases are provided with broad handles. Why?

Why are the parasitic forms of Plathelminthes provided with hooks and sukers, while the free-living forms do not have them?

A bag contains 5 white balls, 7 red balls, 4 black balls and 2 blue balls. One ball is drawn at random from the bag. What is the probability that the ball drawn is: white or blue.

Why are microwave used in Radar?