people have devised ever more cunning tools to cope with work that is dangerous,

people have devised ever more cunning tools to cope with work that is dangerous,
1,work为什么不用复数形式?
2,work后的that能不能用which代替?为什么?
3,conferring为什么双些r加ing?
4,And if scientists have yet to create the mechanical version of science fiction,they have begun to come close.
其中的have yet to 怎么翻译?5,the modern world is increasingly populated by intelligent gizmos whose presence we barely notice
其中we barely notice 为什么不用noticed?
6,Our factories hum to the rhythm of robot assembly arms.
其中的to怎么翻译,哪个是动词.
7,They have built robots that can recognize the error of a machine panel by a fraction of a millimeter
为什么用by?
8,What they found,in attempting to model thought,is that the human brain’s roughly one hundred billion nerve cells are much more talented -- and human perception far more complicated -- than previously imagined.
之中的破折号有什么用?有没有其他的表达形式?
谢谢懂得老师回答!