B．Because they had their own music.

　　C．Because their place was very difficult to reach.

　　D．Because they hadn't been exposed to Western music.

　　解析：D　推理判断题。根据第四段的When they sing or play instruments... apart from the kinds of sounds typical in Western music可知，主要是因为他们没有接触过西洋音乐。

　　3．What do dissonant chords refer to?

　　A．New musical sounds.

　　B．Musical sounds from abroad.

　　C．Unpleasant musical sounds.

　　D．Well­known musical sounds.

　　解析：C　词义猜测题。根据第五段的That term refers to musical sounds that most people consider pleasant to hear. Others were dissonant可知，这里是在进行对比，故后者是被认为不悦耳的音乐。

　　4．What did the researchers most probably conclude in the end?

　　A．Musical preferences are dependent or the environment.

　　B．Musical instruments help people know about music.

　　C．People are born with their musical tastes.

　　D．People love music for different reasons.

　　解析：A　推理判断题。根据文章内容可知，人们对音乐的偏爱受周围的影响。

　　B

　　After years of heated debate，gray wolves were reintroduced to Yellowstone National Park.Fourteen wolves were caught in Canada and transported to the park.By last year，the Yellowstone wolf population had grown to more than 170 wolves.

Gray wolves once were seen here and there in the Yellowstone area and much of the continental United States，but they were gradually displaced by human