Tom realized that he ________ his physicsbook at home when he reached school．

It knowledge is power, ____Sir Francis Bacon wrote in 1579, ______ perhaps creativity ca be described as the ability to use that power.

His writing is so confusing that it’s difficult to make out ________ it is he is trying to express.(2011·安徽，33)

It was in the lab_________was taken charge of by Johnson_________they did the experiment.

______ from space, the earth is blue. [ ]