题目内容：

AC/DC have postponed their US, tour after singer Brian Johnson was warned by doctors that he was at risk of“ total hearing loss". This is unsurprising that the Australian band has been pumping out the hard rock decibel(分贝). But deafness isn't only a concern for rock musicians.  Anyone around music a lot has reason to be equally worried.

When you are exposed to music, risk to hearing arises from a combination of how loud the sound is and how long you' re exposed to it for. If you visit a nightclub with music at 100 dB, then after only 10~15 minutes the exposure is potentially damaging. In a quieter part of the club, but where the music is still loud enough that you have to shout at your friends, them you could be there for a couple of hours before having to worry about your hearing. Of course music frequently exceeds (超过) 80~85 dB, but what counts most in assessing the risk to hearing is the average exposure.

Exposure to high noise levels often causes temporary deafness-something many people have experienced after going to a nightclub. While hearing usually recovers , repeated loud exposure leads to permanent hearing damage. Initially, this damage is unlikely to be noticed by the listener. Problems only become significant in middle age when the noise-caused hearing loss combines with the natural loss of hearing due to ageing.

Often orchestras employ screens or “musicians ear plugs” to block sound from the loudest instruments. These decrease sound without completely blocking everything out and are very useful in rehearsal（训练),but get in the way of balancing the sound in a concert. Professional orchestras also look at how they schedule music to ensure that musicians are exposed to a mixture of quiet and loud pieces. Given how loud their instruments are, drummers are particularly at risk, but using era plugs can go some way to reducing potential hearing loss. For rock and pop musicians, using in-ear monitors has the potential to reduce noise exposure.

Improved technology means the number of musicians having to give up performing could decrease, But student musicians need to be educated about the dangers of noise-caused hearing loss. The increasing use of headphones will also work against this. Unless people are careful with the volume level on their portable music players, hearing loss caused by music will increase.

1.What does the author mainly want to show by mentioning Brian Johnson?

A. Hearing loss are very common nowadays.

B. Music and hearing loss are closely related.

C. Being with music isn't always beneficial.

D. Deafness has become musicians' major concern.

2.What matters most in evaluating the risk of hearing loss according to the text ?

A. The rhythm of music.

B. The average exposure of time.

C. The playing environment of music.

D. The listener's sensitivity to sound.

3.What dose Paragraph 4 mainly talk about ?              .

A. How the sound in a concert is balanced.

B. How professional orchestras schedule music .

C. How musicians can decrease their risk of hearing loss.

D. How different musicians work together in an orchestra.

4.Which of the following best reflects the author's opinion?

A. Improved technology can prevent hearing damage.

B. Student musicians are main sufferers of hearing loss.

C. Using headphones helps reduce hearing loss to a degree.

D. We can never be too careful with the volume level of music.