Experiments in which animals live in artificial surroundings show that

A．Because it is a personal and economic problem as well as a social one.
B．Because it is a totally personal problem.
C．Because it is a huge burden on economics.
D．Because it is social problem.

A．She has been too busy to go to see the paintings yet.
B．She wonders why they can’t take some paintings away.
C．She doesn’t know what the paintings are about.
D．She doesn’t like the paintings by Picasso.