【单选题】It is the third year ____ that he keeps buying milk in glass bottles instead of plastic bottles.
【单选题】It is the third year that he______ in this rented studio.
【单选题】为减少蒸汽中硅酸盐的含量,在运行中锅水应呈碱性,且其PH值最好维持在( )范围内。
【单选题】For Ethiopia and Sudan, it is the second bad year _______ (and the third bad year in four).
【单选题】The first time I ________ here, it was the year of 1980; this is the third time that I _________ to Chongqing.
D.
had come; have visited
【简答题】为减少蒸汽中硅酸盐的含量,在运行中锅水应呈碱性,且其PH值最好维持在()范围内。
【单选题】以下关于金属材料硬度检测的说法中错误的是( )
A.
在采用布氏硬度法进行硬度测量时,布氏硬度值在450以下时,采用淬硬钢球压头;布氏硬度值在650以下时,则采用硬质合金压头
B.
洛氏硬度原理和布氏硬度原理相似,布氏硬度检测时是通过测量钢球所压出的压痕直径来判断出其硬度数值,而洛氏硬度则是通过测量锥体压出的压痕深度
C.
洛氏硬度法测量时所测硬度值重复性优,分散度小,测量时只需取零件表面上的某一点进行检测
D.
维氏硬度法检测时实验载荷可以很小,压痕也较小
【单选题】It is the third time that he ____ abroad on business this year.
【简答题】为减少蒸汽中硅酸盐的含量,在运行中锅水应呈(),且其PH值最好维持在()范围内。
【单选题】为减少蒸汽中硅酸盐的含量,在运行中锅水应呈()