A voice can be hard.Logical formLearned from283 sentences. Shells can be hard.Logical formLearned from282 sentences. A use can be hard.Logical formLearned from280 sentences. A thrust can be hard.Logical formLearned from277 sentences. A piece can be hard.Logical formLearned from273 sentences. A punch can be hard.Logical formLearned from270 sentences. A world can be hard.Logical formLearned from270 sentences. Blows can be hard.Logical formLearned from270 sentences. Information can be hard.Logical formLearned from269 sentences. Covers can be hard.Logical formLearned from268 sentences. An acceleration can be hard.Logical formLearned from266 sentences. A hard drive may pertain-to a computer.Logical formLearned from264 sentences. A tackle can be hard.Logical formLearned from264 sentences. Eyes can be hard.Logical formLearned from263 sentences. Classes can be hard.Logical formLearned from263 sentences.