单选题 Questions 4--8 Complete the following sentences with NO MORE THAN four words for each blank.

填空题 According to theories before quantum theory, atomic energy could lead to 1.

填空题 The contribution Einstein has made is that he discovered the 1, and thus solved the problem with new ideas about light.

填空题 Niel Bohr believed that there is a close correlation between the 1 and 2.

填空题 Niel Bohr developed his theory by using the 1.

填空题 Recent studies suggest that quantum objects are 1, hence the duality in experiments.