阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出一个最佳答案。

    One night in November, Itzhak Perlman gave a concert in a theatre. If you have ever been to a Perlman concert, you know that becoming a violinist is not a small 1 for him. He had to walk 2 the help of two walking sticks as a result of the disease he caught as a child.

    People sat 3 while he made his way to his chair and began his play. But this time, something went 4. Just as he finished the first few parts of the music, one of the wrings(弦) on his violin 5. We thought that he would have to stop the concert. But he didn't. 6, he waited a moment, closed his eyes and then 7 the conductor(指挥) to begin again. The orchestra(管弦乐队) began and he played with such strong feeling and purity as they had 8 heard before.

    Of course, everyone knows that it is 9 for a violinist to play a pleasant work with just three strings. I know that, and you know that, 10 that night Itzhak Perlman didn't want to accept that.

    When he finished, there was a terrible 11 in the room. And then people rose and 12 from every corner of the theatre.

    Perlman was excited. He smiled and said, "You know, sometimes it is the artist's task to 13 how much music you can still make with what you have left."

    So, suppose our task in this fast-changing world is to make 14, at first we should try out best with all that we have. And then,    15 it is no longer possible, try to play it with what we have left.

阅读理解

    Chinese e-commerce websites fail to pay more attention to older consumers, says a news report.

    There's been a thought that younger consumers have been the driving force of online buying. That may not be the case. According to a statement from Alipay, the average expenditure (支出) of Alipayusers born before the 1960s was 31,000 yuan in 2012, much higher than 14,000 yuan of those born after the 1980s. It shows that online shopping has become akey part of people's daily consumption, for both young and old.

    Besides shopping, people pay bills such as water bill, electricity bill, and credit card repayment online. The middle-aged and senior consumers are also participating in that consumption revolution.

    Liu Chen, 56, said that his online expenditure in 2014 was over 50,000 yuan, about half of the total annual expenditure. He always pays his telephone bill online. Clothes, electrical appliances and kids' snacks are themain items he purchases online.

    Liu's shopping strategy is to find something good online first, then go to shops to check it out, and finally buy it online because it is cheaper. As quality concerns him, Liu only buys items that come with aguarantee.

    Stories such as those from Liu are representative of millions of middle-aged and older Chinese, which show the great potential of the aged inthe Chinese consumption market. Yet, the market seems not to be valued as it should be.

    Some Chinese e-commerce websites such as jd. com, dangdang. comand amazon. cn don't have a category for goods for the elderly on their mainpages. Alibaba's platform does have one, but the goods in it are not as abundant as other categories. Moreover, Taobao's category is not really designed for elders, but their children.

    Despite the seeming lack of commitment to older consumers, the Chinese market for the elderly is clearly huge, and e-commerce websites should takegreat efforts to develop it.

某兴趣小组同学为了探究实验室中久置的氢氧化钠固体的成分，进行了有关实验．请你与他们一起完成以下探究活动：