Vocals can be rugged.Logical formLearned from7 sentences. (Avalanche characteristics) can be rugged.Logical formLearned from7 sentences. A jaw can be rugged.Logical formLearned from7 sentences. A plant can be rugged.Logical formLearned from7 sentences. Countries can be rugged.Logical formLearned from7 sentences. An (ocean floor) can be rugged.Logical formLearned from7 sentences. Trunks can be rugged.Logical formLearned from7 sentences. A canyon may be ringed by rugged mountains.Logical formLearned from7 sentences. Rugged mountains can be on a side of a frontier.Logical formLearned from7 sentences. A border may run through rugged mountains.Logical formLearned from7 sentences. A winter can be rugged.Logical formLearned from7 sentences. A (desert frontier) can be rugged.Logical formLearned from7 sentences. (Mountain gorges) can be rugged.Logical formLearned from7 sentences. A northern region can be rugged.Logical formLearned from7 sentences. Loggers can be rugged.Logical formLearned from7 sentences.