False theories can yield true results, so even if an experiment works, it doesn’t prove that the theory it was designed to test it is true.

請問老師 句子中的這個it充當什么成分？

假如去掉這個it， 意思和原來的句子是否一樣？

it doesn’t prove that the theory it was designed to test it is true.

紅字的it是多余的，致使句子結構錯誤，需要刪去，得到：

it doesn’t prove that the theory it was designed to test is true. 劃線部分為定語從句。