The generalized scalar-tensor (GST) theory is modified. In the modified GST theory, the cosmological term Λ is a function of the scalar field φ and of its time derivative φ2 as well. We obtain exact solutions for the scale factor, the scalar field and the cosmological term which evolves with a different dependence on time for each era of the universe. The cosmological 'constant' and flatness problems are examined in the simple case of a flat universe.
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