How can you tell if an argument is valid?

Which statement best explains why shakespeare has cassius use the word fawn rather than a synonym such as flatter to describe his actions?

What is the meaning of the word checking as it is used in this sentence from the second paragraph of the passage?

Read the passage first of all if someone says your dream is impossible, they’re wrong. you can’t prove that something is impossible-all you know is that[it] hasn’t been done yet. people said no one could scale mount everest but in 1953, sir edmund hilary and tenzing norway gazed down upon the world from it’s summit. people said that man could not fly, but in 1903, orville and wilbur wright made the first sustained powered flight in a heavier-than-air machine. people said, “okay, we admit that someone could climb mount everest, and we admit that man has learned to fly, but no one will ever, ever walk on the face of the moon.” if we can send three men a quarter of a million miles away and bring them home safely, is there any great task we cannot accomplish? which identifies the textual evidence that best supports the claim: the authors purpose is to persuade? a: the author shares historical information about the wright brothers. b: the author states that men have walked the moon. c: the author states that others who think your dreams are impossible are wrong. d: the author wants to know what tasks we cannot accomplish.