Albert Einstein is said to have been asked by a student, “ What finding helped you most when you were 1______ the theory of relativity?" Einstein replied without 2______ moment’s hesitation, “Finding how to 3______ about the problem."
The same 4__

Albert Einstein is said to have been asked by a student, “ What finding helped you most when you were 1______ the theory of relativity?" Einstein replied without 2______ moment’s hesitation, “Finding how to 3______ about the problem."
The same 4______ is told about Sir Isaac Newton and 5______ other scientists. We have no proof 6______ any of these well-known conversations 7______ took place, but we are prepared to 8______ that they did, and if so, that the 9______ was the same one Einstein gave, 10______ this is the way scientists work 11______ science progresses.
Scientists usually work toward models of the process or structure they are studying.12______ we have models of the structure 13______ the universe and of the atom, models of the process 14______ which the genetic （遗传的）pattern is passed from one building block of life to 15______， models of the economic system and 16______ on. Some models are mathematical, but a 17______ does not have to have equations（方程式），or even diagrams ； the 18______ requirement is no doubt that it 19______ an insight （洞察力）into the relationships that determine 20______ something works as it does or how it is put together.
15

A.either

B.other

C.both

D.another

正确答案是D