第33题: [单项选择]The policeman kept his eyes ________ on the screen of the computer to identify the criminal's footprints. A. fixed B. fixing C. being fixed D. to fix 参考答案:A 答案解析:“keep one's eyes fixed on sth”意为“眼睛紧盯着……”。
第34题: [单项选择]关于肠道病毒,正确的是 A. RNA病毒 B. 临床表现局限于肠道 C. 抵抗力较弱 D. 包膜病毒 E. 无中枢神经系统病变 参考答案:A