第14题: [单项选择]If the engine does start on air, but combustion does not immediately begin, the cause may be (). A. failure of the fuel pumps B. starting air pressure too low C. stop valve in air line closed D. the turning gear still engaged 参考答案:D
第21题: [单项选择]HIV病毒主要感染的细胞是() A. CD3+T细胞 B. CD4+T细胞 C. CD8+T细胞 D. CD16+/CD56+NK细胞 E. CD19+B细胞 参考答案:B
第22题: [单项选择]What is the meaning of the phrase "come off" in the last paragraph. A. Succeed. B. Take place. C. Get on. D. Fail. 参考答案:A 答案解析:[解析]细节题。根据前后文“whereby dealers illegally arrange beforehand not to bid against each other but nominat