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问题 单项选择题 A1型题

视网膜内屏障的构成，以下说法正确的是

A．由视网膜色素上皮组成

B．介于视网膜与玻璃体之间

C．由视网膜内界膜组成

D．阻挡脉络膜血管内的血液成分渗漏至视网膜内

E．由视网膜血管内皮间的连接复合体组成

答案

参考答案：E

解析：视网膜血管内皮细胞间的连接复合体构成血一视网膜内屏障，血-视网膜外屏障位于色素上皮外。视网膜屏障能阻挡视网膜血管内和脉络膜血管内的血液成分和大分子物质进入视网膜。

问答题

Where one stage of child development has been left out, or not sufficiently experienced, the child may have to go back and capture the experience of it. A good home makes this possible, for example by providing the opportunity for the child to play with a clockwork car or toy railway train up to any age if he still needs to do so. (46)This principle, in fact, underlies all psychological treatment of children in difficulties with their development, and is the basis of work in child clinics.
The beginnings of discipline are in the nursery. Even the youngest baby is taught by gradual stages to wait for food, to sleep and wake at regular intervals and so on. If the child feels the world around him is a warm and friendly one, he slowly accepts its rhythm and accustoms himself to conforming to its demands. (47)Learning to wait for things, particularly for food, is a very important element in upbringing, and is achieved successfully only if too great demands are not made before the child can understand them.
Every parent watches eagerly the child’s acquisition of each new skill — the first spoken words, the first independent steps, or the beginning of reading and writing. (48)It is often tempting to hurry the child beyond his natural learning rate, but this can set up dangerous feeling of failure and states of anxiety in the child. This might happen at any stage. A baby might be forced to use a toilet too early; a young child might be encouraged to learn to read before he knows the meaning of the words he reads. (49)On the other hand, though, if a child is left alone too much, or without any learning opportunities, he loses his natural zest for life and his desire to find out new things for himself.
Learning together is a fruit source of relationship between children and parents. By playing together, parents learn more about their children and children learn more from their parents. Toys and games which both parents and children can share are an important means of achieving this co-operation. Building-block toys, jigsaw puzzles and crossword are good examples.
Parents vary greatly in their degree of strictness or indulgence towards their children. Some may be especially strict in money matters; others are severe over times of coming home at night, punctuality for meals or personal cleanliness. (50)In general, the controls imposed represent the needs of the parents and the values of the community as much as the child’s own happiness and well-being.
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问答题

根据要求完成作图．

（1）如图甲所示，某人站在A处用一根绳子和两个滑轮提起物体B，画出最省力的绕线．

（2）在图乙中，为使杠杆OA保持静止，画出在A点所加最小力F1的示意图和阻力F2的力臂l2．

（3）在图丙中，标出磁感线的方向和小磁针的N极．
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