Vessels can be rugged.Logical formLearned from3 sentences. An engine can be rugged.Logical formLearned from3 sentences. (Rock walls) can be rugged.Logical formLearned from3 sentences. A chain can be constituted-of-or-filled-with rugged mountains.Logical formLearned from3 sentences. A biplane can be rugged.Logical formLearned from3 sentences. An upland can be rugged.Logical formLearned from3 sentences. Rugged mountains may run in some ranges.Logical formLearned from3 sentences. Two-thirds may consist of rugged mountains.Logical formLearned from3 sentences. A central (mountain range) can be rugged.Logical formLearned from3 sentences. Fellows can be rugged.Logical formLearned from3 sentences. A profession can be rugged.Logical formLearned from3 sentences. Toys can be rugged.Logical formLearned from3 sentences. A voice can be rugged.Logical formLearned from3 sentences. A shore can be rugged.Logical formLearned from3 sentences. Laptops can be rugged.Logical formLearned from3 sentences.