Destinations can be challenging.Logical formLearned from5 sentences. An (engineering project) can be challenging.Logical formLearned from5 sentences. Paths can be challenging.Logical formLearned from5 sentences. A campaign can be challenging.Logical formLearned from5 sentences. Fairways can be challenging.Logical formLearned from5 sentences. A yacht can be challenging.Logical formLearned from5 sentences. An adventure can be challenging.Logical formLearned from5 sentences. Identification can be challenging.Logical formLearned from5 sentences. An aircraft can be challenging.Logical formLearned from5 sentences. A (race track) can be challenging.Logical formLearned from5 sentences. A paradigm can be challenging.Logical formLearned from5 sentences. A way can be challenging.Logical formLearned from5 sentences. A trail can be challenging.Logical formLearned from5 sentences. Knowledge can be challenging.Logical formLearned from5 sentences. Management of a disease can be challenging.Logical formLearned from5 sentences.