Ads can be productive.Logical formLearned from17 sentences. Machines can be productive.Logical formLearned from17 sentences. A citizenry can be productive.Logical formLearned from17 sentences. A (work day) can be productive.Logical formLearned from17 sentences. A contact can be productive.Logical formLearned from17 sentences. A (gold mine) can be productive.Logical formLearned from17 sentences. States can be productive.Logical formLearned from17 sentences. (Age groups) can be productive.Logical formLearned from17 sentences. Cooperation can be productive.Logical formLearned from17 sentences. Lands can be productive.Logical formLearned from17 sentences. Gains can be productive.Logical formLearned from17 sentences. A layer can be productive.Logical formLearned from17 sentences. A (learning experience) can be productive.Logical formLearned from17 sentences. Lakes can be productive.Logical formLearned from17 sentences. (Farming areas) can be productive.Logical formLearned from17 sentences.