Norms can be challenging.Logical formLearned from9 sentences. Readings can be challenging.Logical formLearned from9 sentences. An investigation can be challenging.Logical formLearned from9 sentences. (Research areas) can be challenging.Logical formLearned from9 sentences. Individuals can be challenging.Logical formLearned from9 sentences. A homework can be challenging.Logical formLearned from9 sentences. An idea can be challenging.Logical formLearned from9 sentences. Climates can be challenging.Logical formLearned from9 sentences. (Emergency response) can be challenging.Logical formLearned from9 sentences. An (oil field) can be challenging.Logical formLearned from9 sentences. Authorities can be challenging.Logical formLearned from9 sentences. (Industry conditions) may remain challenging.Logical formLearned from9 sentences. A league can be challenging.Logical formLearned from9 sentences. (Crisis points) can be challenging.Logical formLearned from9 sentences. Growth can be challenging.Logical formLearned from9 sentences.