下列化合物最容易被酸水解的苷是
A.2-氨基六碳糖
B.六碳糖
C.七碳糖
D.甲基五碳糖
E.糖醛酸
参考答案:D
解析: 空间位阻小的苷类酸水解容易。
I ______ in a foreign company in Shanghai for six years. Still, I don't regret giving up the well-paid job and returning to my hometown.[ ]
A. worked
B. have worked
C. was working
D. had worked
对限速器安全钳联动试验时,分别以()往下运行,并且在运行过程中,手动托起限速器抛球,让限速器抛块夹住限速器钢丝绳,安全钳应动作。
A.检修速度和平层速度
B.额定速度和检修速度
C.平层速度和额定速度
D.额定速度