基准试剂纯度不够引起的误差属于（）
A.仪器误差
B.系统误差
C.随机误差
D.过失误差
参考答案：B
A _______ number of mothers with young children are stopped from undertaking paid work because they lack access to childcare.
A．considerate
B．critical
C．fundamental
D．substantial
《公民道德建设实施纲要》20字公民基本道德规范是爱国守法、.明礼诚信、团结友善（）
A.和谐向上
B.勤俭自强
C.敬业奉献
