Why do we call the sounds of birds, whales and insects songs? Because something about what we hear seems to have beauty, and some mellifluous (动听的) structure that touches us more than any possible message. Though for many years science has cautioned against hearing too much of what we humans would like to hear when we are trying to understand animal sounds, the musicality in some sounds is now starting to have an effect on the science of animal communication itself.
Many specific animal sounds express aggression(进攻), warning, or food, but such practical explanations are tough to apply to the long songs. Some whale songs can go on for up to 24 hours. The usual explanation for birdsong is that the birds are singing to attract mates or to announce the limits of their area. But the audience is not always evident for these long love songs, which have many of the elements related to human music: rhythm, melody (旋律), themes, repeating patterns, organization, variety, interest — all adding up to something humans have found beautiful for thousands of years. “Birds taught man,” wrote Roman poet and philosopher (哲学家) Lucretius, “and taught them songs before their art began.”
What is the scientific value of such sounds? The advantage of hearing music in nature and trying to reach out to nature through music is that though we don’t fully understand it, it is so accessible.
Music refuses explanation, but it clearly expresses something deep and important, which humans can’t live without. Finding music in the sound of birds, whales and other animals makes the farther frontiers(边缘) of nature see much closer to us.
The underlined phrase “cautioned against” in Paragraph 1 probably means “_______”.

A．warned against

B．fought against

C．been filled with

D．been satisfied with

According to the passage, which of the following is NOT true?

A．We call the songs of birds’ sounds because there is beauty that sounds pleasant to the ears.

B．It is believed that birds are singing to attract mates or to warn the limits of their areas.

C．The songs of a bird really carry an emotional message such as “aggression and caring”.

D．It is not very long for people to know that birdsong does have something beautiful.

By saying “Birds taught man”, what did Lucretius mean?

A．People teach rhythm, melody, themes, repeating patterns to birds.

B．Birds can teach people how to go on singing a song up to 24 hours.

C．Human music has, in fact, come from the sounds of birds in nature.

D．Humans learned something beautiful from the sounds of many animals.

From the passage we know that music in nature ________.

A．can’t be explained at all

B．is very easy to pick up and listen to

C．can’t be understood at all

D．is of no scientific value