Works can be challenging.Logical formLearned from119 sentences. A content can be challenging.Logical formLearned from118 sentences. A look can be challenging.Logical formLearned from115 sentences. Periods can be challenging.Logical formLearned from113 sentences. Music can be challenging.Logical formLearned from111 sentences. A case can be challenging.Logical formLearned from111 sentences. Positions can be challenging.Logical formLearned from110 sentences. Some problems can be challenging.Logical formLearned from109 sentences. Missions can be challenging.Logical formLearned from108 sentences. An activity can be challenging.Logical formLearned from107 sentences. Schools can be challenging.Logical formLearned from106 sentences. Markets can be challenging.Logical formLearned from106 sentences. An undertaking can be challenging.Logical formLearned from105 sentences. An (operating environment) can be challenging.Logical formLearned from105 sentences. A year can be challenging.Logical formLearned from104 sentences.