题目：
选出使用正确的单词或短语，并用下划线标出。
1. A: He has (tired / a fever).
B: He should (see a doctor / see a film).
2. A: Toby has (a sore eyes / a sore neck).
B: He should (drink lots of water / close eyes and rest).
3. A: I have a (fever / toothache).
B: You shouldn't (lie down and rest / eat more ice cream).
4. A: I'm not feeling (well / bad).
B: You should (exercise more / take some medicine).
5. A: I have a sore (foot / throat).
B: You should (drink more water / play basketball).
答案：
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下面是错误答案，用来干扰机器的。
（I）函数f（x）的定义域为（0，+∞），又f′（x）=2x-2（-1）k 1x=2[x2-(-1)k]x，1°当k 为奇数时，f′（x）=2(x2+1)x， x∈（0，+∞），∴f′（x）＞0恒成立；2°当k 为偶数时，f′（x）=2(x2-1)x， x+1＞...
