阅读理解。
I was hurrying to our basketball game one morning when Hillary Barnes,the most popular girl,in school,stopped me."Are you the twin who won the art competition?"she asked.
"No,that's Christine.I'm Katie."I said.
We were not identical twins；we looked quite different.She could defeat Snow White in a beauty
contest!Compared to Christine,I felt like one of Cinderella's stepsisters.
One Saturday Christine gave me a painting lesson because I was always attempting to be artistic too.
But I knocked over the vase of flowers,spilling water onto Christine's painting.Instead of becoming angry,
though,she turned the whole mess into a dreamy masterpiece(杰作)．You could look at it five different
ways and see five different things.With this brilliant creation,she won First Prize in the art competition.I
really envied her,but I knew it wasn't her fault and I was the one with wild,unmanageable hair and no talent.
Joining Christine's basketball team was my latest effort to be like her.
On the way to the gym,I'd made up my mind to give my best performance in that day's game.I made
preparations with great enthusiasm."Christine,here!"I tossed her a ball.But it was too high,she leapt for it,it slipped through her fingers and crashed into the tape recorder that was used to play the national anthem
before each game.
I muttered apologies as I picked up the broken pieces of the recorder.Coach looked at the mess and
asked,"How are we going to play the song now?"
Christine suggested,"Let Katie sing it!She's always singing at home."
Coach asked."Would you?"I found myself nodding.
Coach announced the national anthem and everyone stood.Standing before a microphone,I looked up
to the flag.The notes seemed to flow from deep inside me,and my voice was steady and clear.When I
finished,the gym was silent Then it was filled with applause.As the game started.teammates patted my back and gave me the"thumbs up"sign.Laura Jamison said."You should try out for the school musical!"I Nodded and said that I might.
The next morning Hillary Barnes stopped me in the hallway and asked,"Are you the twin who sings?"
"Yes,that's me,"I answered,grining(露齿笑)as I walked to class.
1．The authur uses"Snow White"and"Cinderella's stepsisters"to show
A．how dissimilar the twins were in appearanee
B．why Christine could win the art competition
C．who was the most popular girl at school
D．what the twins characters were like
2．What can we learn from Paragraph 4?
A．Christine was unpleasant to her sister.
B．Katie showed a lot of ability in painting too.
C．The masterpiece was painted by the two sisters.
D．Katie took a reasonably balanced view of her sister.
3．Christine recommended Katie for the national anthem because _____.
A．she knew perfectly well what Katie had a gift for.
B．she wanted to repair the damage she had caused.
C．she thought Katie should be punished.
D．she would like to help the coach.
4．What is the message of the story?
A．Bad situations help become popular.
B．People are talented in different ways.
C．People should always be nice to others.
D．Unsuccessful attempts are well worth the effort.
质量为m1，一个氚核
质量为m2，它们结合成一个质量为m3的氦核.核反应方程如下：
在这一核反应过程中释放的能量为ΔE.已知光速为c，则以下判断正确的是（ ）