用X射线透照小径管,DL/T821-2002允许的黑度范围为(),JB/T4730、2-2005允许的黑度范围为()。
参考答案:1.5≤D≤3.5;1.5≤D≤4.0
日本花柏
A well-written speech ______ a lot, such as a good choice of words, a clear
structure, a distinct theme, etc.
A.calls on
B.calls for
C.calls up
D.calls off