The speaker mainly discusses________.

Culture can be defined as behavior that is learned and transmitted to members of a group. A child learns a particular behavior through observation as well as through positive and negative feedback from his/her family and peers. A minor point to remember is that this feedback can be overt or covert. Much covert feedback involves nonverbal cues that an outsider to that culture would not understand.

Most waves are caused by winds, though earthquakes on the ocean bed can also cause them, and tides are caused by the effect of the gravity of the moon on the earth and also, although to a lesser extent, the sun’s gravity. One bulge of water is drawn upon the side of the earth actually facing the moon; another bulge of water is drawn on the earth’s far side.