A stage can be difficult.Logical formLearned from643 sentences. Subjects can be difficult.Logical formLearned from638 sentences. Comparisons can be difficult.Logical formLearned from636 sentences. A person may find difficult.Logical formLearned from633 sentences. Access can be difficult.Logical formLearned from630 sentences. An economic environment can be difficult.Logical formLearned from627 sentences. A (balancing act) can be difficult.Logical formLearned from614 sentences. A battle can be difficult.Logical formLearned from612 sentences. A struggle can be difficult.Logical formLearned from603 sentences. A balance can be difficult.Logical formLearned from586 sentences. A group can be difficult.Logical formLearned from580 sentences. Months can be difficult.Logical formLearned from580 sentences. Words can be difficult.Logical formLearned from571 sentences. Steps can be difficult.Logical formLearned from555 sentences. Travel can be difficult.Logical formLearned from552 sentences.