问题 多项选择题

从功能角度分析,______不能直接完成机器预定功能且不能作为机器设备区分和分类的主要依据。

A.动力部分

B.传动部分

C.工作部分

D.控制部分

E.制动部分

答案

参考答案:A,B,D,E

解析:工作部分是直接完成机器预定功能的部分,如车床的刀架;车辆的车厢;飞机的客舱、货舱等。工作部分是机器直接进行生产的部分,是机器用途、性能综合体现的部分,是机器设备区分和分类的依据。动力部分、传动部分以及控制部分都应该根据工作部分的功能要求、运动参数和动力参数的合理范围进行设计和选择。它们是为实现工作部分的技术能力而服务的。

多项选择题
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Tail Spin

Two dolphins race around in a big pool in the Ocean Park. The smaller dolphin Grace, shown off a few of her tricks, turning around and waving hello to the crowd. The most amazing thing about her, however, is that she’s even swimming at all. She doesn’t have a tail.

Grace lost her tail as a baby when she got caught up in a fish trap.

When the dolphin arrived at the Ocean Park in December 2005, she was fighting for her life. “Is she going to make it?” Her trainer, Abbey Stone, feared the worst. Grace did make it — but her tail didn’t. She ended up losing her flukes and the lower part of her peduncle.

Over the past six years, she has learned to swim without her tail. Dolphins swim by moving their flukes and peduncle up and down. Grace taught herself to move another way—like a fish! She pushed herself forward through the water by moving her peduncles from side to side.

The movement put harmful pressure on Grace’s backbone. So a company offered to create a man-made tail for her. The tail had to be strong enough to stay on Grace as she swam but soft enough that it wouldn’t hurt her.

The first time Grace wore the artificial tail. She soon shook it off and let it sink in the bottom of the pool. Now, she is still learning to use the tail. Some days she wears it for an hour at a time, others not at all. “The tail isn’t necessary for her to feel comfortable,” says Stone, “but it helps to keep that range of motion(动作) and build muscles(肌肉).”

Now, the dolphin is about to get an even happier ending. This month, Grace will star in Dolphin Tale, a film that focus on her rescue and recovery. Her progress has inspired more than just a new movie. Many people travel from near and far to meet her. Seeing Grace swim with her man-made tail gives people so much courage.

小题1:When Grace first arrived at the Ocean Park, her trainer worried about her .

A.physical build

B.potential ability

C.chance of survival

D.adaptation to the surroundings.小题2:A man-made tail is created for Grace to     .

A.let her recover faster

B.make her comfortable

C.adjust her way of swimming

D.help her perform better tricks小题3:The story of Grace inspires people to   .

A.stick to their dreams

B.treat animals friendly

C.treasure what they have

D.face difficulties bravely