四、翻译下面各句中的划线部分。 1. It’s slippery, so mind where you’re walking. 2. Kelly is picking up wonderfully since she came out of hospital. 3. Perhaps you can help me pick out a pair of jeans, since you are an expert. 4. It took them three years to pay off their debts. 5. We picked up their tracks again on the other side of the river. _________