A gravitational field of a black hole can be strong.Logical formLearned from1 sentences. A gravitational field can be at a surface of a star.Logical formLearned from1 sentences. Gravitational forces may lead to variety of effects.Logical formLearned from1 sentences. A gravitational force can be proportional to an inverse of a square of a distance.Logical formLearned from1 sentences. A gravitational force can be between stars.Logical formLearned from1 sentences. A separation may determine a gravitational force.Logical formLearned from1 sentences. A matter may provide a gravitational force.Logical formLearned from1 sentences. Gravitational attraction may increase a (dust concentration).Logical formLearned from1 sentences.