• [A] chair
• [B] light
• [C] floor
• [D] desk
• [E] window
• [F] door
• [G] blackboard

People turn it on to make a room brighter.

A．People can know the weather hundreds of years ago by studying the tree ring.
B．People can study the history of man from tree rings.
C．People can know what animals had once lived from tree rings.

A．more and more
B．less and less
C．many and more