第11题: [单项选择]What happened to the cats if the number of mice in a post office didn’t decline within 6 months A. They were killed. B. They were punished by not to be given food. C. They had to change job. D. They were dismissed. 参考答案:D
第17题: [单项选择]人类白血病的病因尚不完全清楚,目前认为最有可能的是()。 A. 病毒 B. 电离辐射 C. 化学因素 D. 遗传因素 E. 其他血液病 参考答案:B 答案解析:一般骨髓干细胞内的DNA变异导致它们的恶化,其原因可以是暴露在放射线中、接触致癌物质和其他细胞内遗传物质的变异,病毒也可能导致白血病。