Long life is altering our society, of course, but in experimental terms.fficeffice" />

What does the red part mean ?  冲刺（四）6

Historians are detectives searching out the evidences of the past in their pursuit of history. This is a challenging and frequently engaging quest on its own, but evidence must turned to account. Primary sources that are uncovered present many forms that vary with the questions asked and the priod studied.

Historians are detectives searching out the evidences of the past in their pursuit of history. This is a challenging and frequently engaging quest on its own, but evidence must turned to account. Primary sources that are uncovered assume many forms that vary with the questions asked and the priod studied.

Which is correct? Why ?  冲刺（六）1

  The reason why 94% of crimes do not result in a conviction is that three-quarters of them are not cleared up , and so nobody is charged.  What does the red part mean here ? 冲刺（六）3

  The invention of new materials and welding techniques are responsible for much of the changes in sculpture arts. 

  Does the “much of” here just mean “many” or does it mean “the most of “? 冲刺（六）5

  The example of ozone reduction is used to show the difficulty in balancing forcing-feedback interactions.

 Forcing refers to radiative forcing（热辐射作用力）   feedback refers to radiative feedback

  difficulty in sth : 是表示“做某事的困难”还是“某事的复杂性”还是两者皆可？

  What does the red part mean ?  冲刺（六）8