A challenge may pertain-to a country.Logical formLearned from140 sentences. A person may win a challenge.Logical formLearned from139 sentences. Challenges may face persons.Logical formLearned from139 sentences. Challenges can be persistent.Logical formLearned from139 sentences. Challenges can be unforeseen.Logical formLearned from139 sentences. A challenge can be awesome.Logical formLearned from139 sentences. A challenge can be for a title.Logical formLearned from139 sentences. A challenge may pertain-to a continent.Logical formLearned from139 sentences. A day can be a challenge.Logical formLearned from138 sentences. A challenge may pertain-to a season.Logical formLearned from138 sentences. Challenges may be faced.Logical formLearned from138 sentences. Challenges can be from a country.Logical formLearned from138 sentences. A challenge can be formidable.Logical formLearned from137 sentences. Challenges can be steep.Logical formLearned from137 sentences. A challenge can be to a system.Logical formLearned from137 sentences.