题干

汽车用铅蓄电池中需要质量分数为28%的稀硫酸。若在实验室中用10g质量分数为98%的浓硫酸(密度为1.84 g/cm3)配制28%的稀硫酸,下列做法或说法正确的是(水的密度近似看作1g/cm3)(   )

A:将25mL水慢慢倒入盛有5.4mL浓硫酸的量筒中,并用玻璃棒不断搅拌

B:将10g98%的浓硫酸沿烧杯壁慢慢注入盛有25mL水的烧杯中,并用玻璃棒不断搅拌

C:若其他操作正确,量取25mL水时俯视读数,则所配稀硫酸中溶质的质量分数小于28%

D:配制该溶液时,若有浓硫酸沾到手上应立即用氢氧化钠溶液中和

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B

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    On Sunday 23 April, more than 30, 000 people participated in the 2017 London Marathon, running 26.2 miles (42.2 kilometers) around the city centre.

    The London Marathon has taken place every year since 1981. At the first one just6,225 people completed the course, and since then it has grown into one of the biggest sporting events in the world. It is one of the “World Marathon Majors”, which is a competition made up of six global marathon events. The overall male and female winners receive $ 1 million in prize money between them. There are eleven people who have run every London Marathon since it began—they call themselves the “Ever Presents”.

    This year, the winners of the London Marathon were surprisingly both from Kenya— Daniel Wanjiru, who finished in 2 hours and 5 minutes, and Mary Keitany, whose time was 2 hours and 17 minutes.

    However, most marathon runners are not professional athletes. They are amateurs who have trained for months to raise money for charity or just as a personal challenge. For example, Tom Harrison took three days just to reach the run's halfway point, as he is crawling the course on his hands and knees dressed as a gorilla(大猩猩), trying to raise money and attention for the charity “The Gorilla Organization”.

    Matthew Rees was another runner to encourage people, as he stopped just before the finish line to help David Wyeth run the last 200m. They did not know each other before, but Matthew saw that David was exhausted and possibly close to collapsing, and wanted to help him finish.

    Every year there are lots of touching stories like this from the London Marathon, and it is a huge achievement even to run the 26.2 miles!