用方框中所给单词的适当形式填空，每空仅用一词（每空一词）。

    Some scientists believe that there will berobots in the future. , they agree it may take hundreds of years. These new robots will have many different . Some will look like humans, and others might look like animals. This was 20 years ago, but computers and rockets also seemed not possible 100 years ago. We never know what will in the future.