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问题 选择题

砷为第四周期 VA族元素，根据它在元素周期表中的位置推测，下列说法不正确的是

A．砷可以有-3、+3、+5等多种化合价

B．砷原子的第3电子层含有18个电子

C．H3AsO4的酸性比H3PO4弱

D．砷的氢化物的稳定性比磷化氢的强

答案

答案：D

填空题

Every object tells a story. Even the most ordinary objects can present to us powerful images. Sometimes it is the ordinary nature of these objects that actually makes them so extraordinary. Such is the case with an old leather shoe in a museum in Alaska. At first glance it does not look like much. It is a woman’s shoe of a style popular in the 1890s. But what is unique about this shoe is where it was found. It was discovered on the Checkout Pass, the famous trail used by the people seeking gold in Alaska. Who it belonged to or why it was left there is not known. Was it perhaps dropped by accident as the woman climbed up the 1500 stairs carved outface Or did she throw away goods that she didn’t need in order to travel lighter
Over 100000 people with "gold fever" made this trip hoping to become millionaires. Few of them understood that on their way they would have to cross a harsh wildness. Unprepared for such a dangerous journey, many died of starvation and exposure to the cold weather.
The Canadian government finally started requiring the gold seekers to bring one ton of supplies with them. This was thought to be enough for a person to survive for one year. They would carry their supplies in backpacks each weighing up to fifty pounds; it usually took at least 40 trips to get everything to the top and over the pass. Whoever dropped the shoe must have been a brave and determined woman. Perhaps she was successful and made it to Alaska. Perhaps she had to turn back in defeat. No one will ever know for sure, but what we do know is that she took part in one of the greatest adventures in the 19th century.

The ordinary woman’s leather shoe is considered unusual because ______.
A. it was an important clue to life in the past
B. it was found on a famous trail
C. it at one time belonged to a VIP
D. it was a fashionable shoe at that time
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单项选择题 A1/A2型题

影响血液黏度的内在因素中不包括（）

A.血细胞比容

B.红细胞聚集性

C.红细胞变形性

D.血浆黏度

E.切变率
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