For example on number 1 the time signature is 4/4 , that means there has to be 4 beats in between each bar line. They have already put in a half note which is equal to 2 beats. You can either put another half note or two quarter notes.
Remember
Whole Note = 4 beats
Quarter Note = 1 beat
Half Note = 2 beats
Dotted Half Note = 3 beats
Answer: Do you have a link to the statements??
Explanation:
Classical Greek choruses consisted of a group of actors who delivered lines in unison. Their lines in the play were usually a commentary on the action/plot of the play, and they acted as a stand-in for the audience.