工作前检查液压油量，油缸活塞伸出约250mm时，泵站油箱内油面高度应达到油箱高度的（

Arctic fox(北极狐) is a kind of small fox that lives in the Arctic. It grows about 50 centimeters long, not including its tail, 30 centimeters tall and weighs from 3 to 7 kilos.

The Arctic foxes are white or blue in color. The white ones are white in winter, but grey-brown in summer. The blue ones are blue-grey all year round. The Arctic foxes have long, thick hair that is called fur. And the long fur covers their whole bodies, including both their cat eyes and rabbit feet, to keep them warm in the low temperature in the Arctic.

The Arctic foxes feed mainly on birds, birds’ eggs and other small animals. Teamwork is the way they look for food, and they don’t like to do that alone.

Baby Arctic foxes are very lovely. They don’t open their eyes until a week after their birth. For the first half of the year, their parents offer them food. They begin to look for food on their own when they are about six months old. The next year they can live alone.

Today, the number of the Arctic foxes is becoming smaller and smaller, because people kill them for their fur to make beautiful coats for money. Something must be done to protect the Arctic foxes.

小题1:Not all the Arctic foxes change their colors in different seasons.

小题2: The Arctic foxes have rabbit eyes and cat feet.

小题3: Baby Arctic foxes are born with their eyes open.

小题4: Birds, birds’ eggs and other small animals are the main food for the Arctic foxes.

小题5: According to the passage, there are more Arctic foxes now.

为验证铁、铜、铝三种金属的活动性顺序，可选用的一组物质是（　　）

A．FeSO₄溶液、Cu、AlCl₃溶液

B．CuSO₄溶液、Fe、AlC1₃溶液

C．CuSO₄溶液、Fe、Al

D．AlCl₃溶液、Fe、Cu

在测定条件有小的变动时，测定结果不受影响的承受程度是

A．准确度
B．精密度
C．专属性
D．线性
E．耐用性

“吃不到葡萄说葡萄是酸的”是属于哪种心理防御机制（）

A.转移

B.合理化

C.否认

D.升华

E.幻想