What does the phrase “socrates knew how little he knew” mean

Restricting immigrants from entering a country may be based on what belief?  

What was the main idea behind the daoist religion? a. everyone's life was guided by moral behavior. b. to live peacefully meant to live a life of suffering. c. family should be put above all else. d. all things should follow the flow of nature.

Music the height of a wave or the amount of the wave carries is the amplitude. a.air b.nodes c.speed d.energy