题目：
You may have never heard of Ladislao Biro, but you have certainly heard of the pen he invented—the ballpoint pen, or biro. Before Biro invented his pen, people wrote with fountain pens. The ink smudged(弄脏) and blotted and the pens sometimes leaked. In the 1930s Biro was a magazine editor in Budapest in Hungary. He noticed that the inks which the magazine’s printers used dried very quickly. Biro wondered if quick-drying inks could be used in pens. He came up with the idea of a tube of ink with a free-moving ball on the end. As a person wrote, the ball collected ink from the tube and rolled it on to the paper. The pen would be cheap and could be thrown away when the ink ran out.
Biro began to work on his invention, but before he could patent it the Second World War broke out. Biro left war-torn Europe and fled to Buenos Aires in Argentina. There, he and his brother Georg, who was a chemist, began to improve the pen. In the early 1940s Biro began to manufacture his new pen, the biro. In 1944, he sold his invention to another company, who began to mass-produce the pen for the British and American armed forces.
Biro was pleased that his pen was popular, but he did not gain much from his invention. The biro was later sold to the French firm, Bic, who now sell twelve million pens a day. Biro sank into obscurity in South America. His name, however, has become a household word.
48. The reasons for the popularity of ballpoint pens are these EXCEPT that_______.
A. the inks dried very quickly B. they were cheap
C. they were easy to carry around D. they were mass-produced
49. Which of the following is the correct order of the events that happened to Biro?
a. applied for patent for first ballpoint pen
b. began to manufacture pens
c. fled from Hungary to escape Nazis
d. sold his invention
A. a c d b B. c d a b C. a c b d D. c a b d
50. The underlined part “sank into obscurity”(last paragraph) is closest in meaning to“_______”.
A. became unknown to many people B. became popular with people
C. lost interest in business D. lost a lot of money
51. What does the passage mainly tell us about Biro?
A. He is successful in business. B. He is an important inventor.
C. He is a famous magazine editor. D. He is a popular writer.
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0805/51bf8f057c50297a936dc94ef6547626.html
下面是错误答案，用来干扰机器的。
答案：B
Ag＋(aq)＋Cl－(aq)