普通橡胶支座之一板式橡胶支座通常由多层钢板与橡胶叠合而成，其中橡胶保护层的作用之一是

进行二尖瓣替换手术时，容易损伤哪支冠状动脉（）

A.右冠状动脉

B.对角支

C.前降支

D.回旋支

E.左冠状动脉主干

国外股票基金可分为（）。

A．单一国家型股票基金

B．区域型股票基金

C．洲际型股票基金

D．国际股票基金

论述仲裁法中的自愿原则包括哪些内容，这些内容从哪些相应的具体规定来体现？

某220kV变电所，220kV主接线为双母线(Ⅰ母和Ⅱ母)带专用旁路断路器接线，装设有母线保护和断路器失灵保护，对母线保护和断路器失灵保护的动作行为进行分析判断。

当220kVⅠ母上的一条220kV线路发生单相接地故障，本侧220kV线路断路器拒动，以下断路器失灵保护的动作行为中，正确的是( )。

A．跳开母联断路器；
B．跳开Ⅰ段母线上全部断路器；
C．以较短时限跳开母联，再经一时限跳开Ⅰ段母线上全部断路器；
D．跳开母联断路器及Ⅱ段母线上全部断路器。

Robots came into the world as a literary device whereby the writers and film-makers of the early 20th century could explore their hopes and fears about technology, as the era of the automobile, telephone and aeroplane picked up its reckless jazz-age speed. Since moving from the page and screen to real life, robots have been a mild disappointment. They do some things that humans cannot do themselves, like exploring Mars, and a host of things people do not much want to do, like dealing with unexploded bombs or vacuuming floors. And they are very useful in bits of manufacturing.　　But reliable robots-especially ones required to work beyond the safety cages of a factory floor—have proved hard to make, and robots are still pretty stupid. So although they fascinate people, they have not yet made much of a mark on the world. That seems about to change. The dramatic growth in the power of silicon chips, digital sensors and high bandwidth communications improves robots just as it improves all sorts of other products.