（）在碱性条件下很稳定，故碱水解法仅适合这种氨基酸的含量测定。
A、精氨酸
B、丝氨酸
C、苏氨酸
D、色氨酸
参考答案：D
对我国影响最大的气候灾害是： [ ]
A．寒潮
B．台风
C．水旱灾害
D．地震
They____to settle in the countryside after they retired in the city. [ ]
A. made up their minds
B. made up their mind
C. change their minds
D. keep their mind
