【单选题】下面哪种调查方式的样本不是随机选取的( )
D.
判断抽样 prefix="o" ns="urn:schemas-microsoft-com:office:office"? ?xml:namespace>
【简答题】A.He was not hungry. B.He had already had his breakfast. C.He was too tired. D.He wanted to sleep a little more.
【单选题】His aunt wanted to have him _______ the radio, but he had had it ________ already.
【简答题】By the time he was ten,Edison______experiments in chemistry. A.had already done B.already had done C.was already doing D.already did
【单选题】酶活力国际单位的定义是
A.
在最适条件下,每分钟催化1mmol底物反应所需的酶量
B.
在最适条件下,每分钟催化1mmol底物反应所需的酶量
C.
在37℃条件下,每分钟催化1mmol底物反应所需的酶量
D.
在实验室条件下,每秒钟催化1mmol底物反应所需的酶量
E.
在实验室规定条件下,每分钟催化1umol底物反应所需的酶量