Why did the introduction of sound into film initially impede the movements of actors?

Read the excerpt from the building of manhattan. the heater cranked the blower handle to force air up through the fire and heat the rivets in the furiously burning bed of coals. he knew how hot the rivets were by the way their color changed. cherry-red rivets were 1,000 to 1,950 degrees fahrenheit. at the right moment he grabbed one in his tongs and tossed it to the catcher. which phrase cannot be changed in a paraphrase of this text? “the furiously burning bed of coals” “by the way their color changed” “1,000 to 1,950 degrees fahrenheit” “force air up through the fire and heat”

Acurious child asked his mother: “mommy, why are some of your hairs turning grey? ” the mother tried to use this occasion to teach her child: “it is because of you, dear. every bad action of yours will turn one of my hairs grey! ” the child replied innocently: “now i know why grandmother has only grey hairs on her head.”

Some have called jazz music “america’s classical music.” what is meant by this statement? do you agree or disagree?