C．To show cloned animals are very different from each other.

D．To prove cloning is not a good way to bring pets from the dead.

解析：选D　推理判断题。由第三段中的"but research on cloned cows and pigs has so far shown marked differences in behavior and even looks in cloned animals. The DNA is exactly the same, but there are still differences in personality and appearance."可知，作者提到关于克隆牛和猪的研究是为了说明克隆出来的宠物会与原来那个宠物不一样，因此克隆并不是一个挽回自己原有宠物的好方法。

3．What will the couple be likely to find out about their new dogs?

A．They'll grow in a very strange way.

B．They'll dislike their new environment.

C．They'll act differently from Shannon.

D．They'll have the same personality as Shannon.

解析：选C　细节理解题。由最后一段中的"the new dogs will still behave differently"可知，这对夫妇会发现他们的克隆狗与原来的Shannon在行为举止上并不相同。

4．What was Piedrahita's attitude towards the lab's promise of pet cloning?

A．He disbelieved it.

B．He was worried about it.

C．He was cautious about it.

D．He showed much interest in it.

解析：选A　推理判断题。由最后一段中的"that will not be the case"可知，Piedrahita并不相信这样的承诺。

I am a member of the Young People's Chorus (YPC) of New York City. The chorus is made up of children aged 8 to 18.I've been in the chorus for almost five years, and I love the community of "young artists." Every year, we give a big performance to raise money for the organization. It's the biggest concert of the year and is held at Lincoln Center. A lot of work goes into the final performance.

First, we begin learning our music. We usually start by learning the notes, and then we add the words. Someone comes in to teach us the meaning and pronunciation of the lyrics (歌词) if the words are not in English.

Next, we memorize the whole song, even if we only sing part of it. One of the hardest pieces we sang this year was Tjak！， a song inspired by a Balinese Monkey Chant. It has four parts, each with a different rhythm.

Once we add dynamics (力度变化) to our songs to give them life, it's time to add choreography. Jacquie Bird, the director, tells us to connect the words we sing to our movements as we breathe and count in our heads.

As we get closer to the concert night, the rehearsals (彩排) get tougher. Sometimes, we do a quick review, and sometimes we sing the whole song. My knees and arms start to ache. But once we get a break and some food, we come back feeling better. We rehearse on weekends for almost a month beforehand; every moment i s important and worth it.

The real excitement comes during the rehearsal, when we meet our guest artists. This year, YPC invited Mandy Gonzales, Alexandra Socha, and Time for Three to join us. After hearing that we would work with them, we jumped up and down backstage