阅读下面短文，掌握其大意，然后从21-30各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。

阅读下面短文，掌握其大意，然后从21-30各题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。
One day, Miss Ellis gave her pupils a new kind of homework: homework on happiness. Her pupils would be “happiness     1   ”, and were to see what would happen when they tried to bring happiness to those around them. As part of their homework, all the students did really    2   , wonderful things, but what Carla Chalmers did left everyone    3   . Several days after the homework had been handed out, Carla turned up carrying a big bag.
“Here in this bag I have all the happiness I’ve collected so far,” she said    4   . On seeing this, everyone was filled with    5   , but Carla didn’t want to show anyone what was in the bag. Instead, she pulled out a small box and gave it to her teacher. When Miss Ellis had taken the box, Carla took a(n)    6    camera out of her own pocket and stood with it at the ready.
“Open it, Miss Ellis.”
The teacher slowly opened the box and looked inside. A big smile    7    on her face, and at that moment Carla took a photo, Carla’s photo came out of the camera immediately, and she    8     it to Miss Ellis along with a sheet of paper. The teacher read the paper in silence, and when she, had finished, she gestured at the    9   .
“Oh, so it’s…”
“Yes!”    10    Carla, opening the bag. “It’s a great big pile of smiles!”
She opened the bag and photos of different    11    fell out.
The rest of the class tried to    12    how Carla had managed to create such a great big chain of happiness. All there in the box was a photo of a big smile. But everyone who had seen it felt happiness being transmitted（传送）to them, and in return, without    13   , every person    14    with a  smile of their own.
She managed to    15    understanding of the smile truth that every time you smile you are sending a gift to the world.

小题1:	A．explorers B．instructors C．players D．collectors

小题2:	A．regretful B．delightful C．stressful D．thankful

小题3:	A．surprised B．satisfied C．annoyed D．depressed

小题4:	A．disappointedly B．sadly C．amazedly D．smilingly

小题5:	A．astonishment B．kindness C．expectation D．pride

小题6:	A．expensive B．old–fashioned C．instant D．good-looking

小题7:	A．disappeared B．froze C．faded D．shone

小题8:	A．offered B．sold C．packed D．paid

小题9:	A．box B．bag C．camera D．pocket

小题10:

A．added B．questioned C．replied D．interrupted

小题11:

A．smiles B．teachers C．ceremonies D．friends

小题12:

A．try out B．focus on C．decide on D．figure out

小题13:

A．imagination B．expression C．hesitation D．reason

小题1:D

小题2:B

小题3:A

小题4:D

小题5:C

小题6:C

小题7:D

小题8:A

小题9:B

小题10:D

小题11:A

小题12:D

小题13:C

小题14:A

小题15:D