三相交流异步电动机在起动时电源缺相,电机将出现()。
A.异常声响
B.正常转动
C.转速很低
D.不能转动、无声
参考答案:A
从下列几个选项中选出你认为错误的一项[ ]
A.由于得罪了瓦西里神父,保尔被学校开除了,母亲把他送到了车站食堂里去做杂工。
B.保尔在路边上从押送兵手中解救出朱赫来,后因维克托的告密而被捕。
C.《筑路》表现了保尔和战友们为保卫年轻的无产阶级革命 * * ,在极端艰难困苦的条件下显现出的英雄本色。
D.保尔在双目失明、瘫痪在床的情况下,完成了自传体小说《钢铁是怎样炼成的》。
课文和新概念填空(共10题;每小题1分,共10分)
John Snow was a famous doctor in London - so 1 , indeed, that he 2 Queen Victoria as her personal physician. But he became inspired when he thought about helping ordinary people 3 to cholera. This was the 4 disease of its day. Neither its cause nor its cure was understood. So many thousands of terrified people died every time there was an outbreak. John Snow wanted to face the 5 and solve this problem. He knew that cholera would never be controlled until its cause was found.
At last firemen have put out a big forest fire in California. Since then, they have been trying to find out how the fire began. Forest fires are often caused by broken glass or by cigarette ends which people carelessly throw away. Yesterday the firemen 6 the ground carefully, but were not able to find any broken glass. They were also quite sure that a cigarette end did not start the fire. This morning, however, a fireman 7 discovered the cause. He noticed the 8 of a snake which was wound round the electric wires of a 16,000-volt power line. In this way, he was able to solve the mystery. The 9 was simple but very unusual. A bird had 10 the snake from the ground and then dropped it on to the wires. The snake then wound itself round the wires. When it did so, it sent sparks down to the ground and these immediately started a fire.