S1. Teaching is a highly-complex occupation because________.

A．The ticket cost nothing, so he shouldn’t worry.
B．The man can buy the ticket of her roommate.
C．The man needn’t pay anything since her roommate decided to pull out of going.
D．She will sell her ticket to her roommate.

A．Children’s IQ and TV.
B．The time children spend watching TV.
C．The effect TV has on learning.
D．The amount of time the average child spends watching TV.