当允许在表面粗糙度参数的所有实测值中不得超过规定值时,应在图样上标注表面粗糙度参数的()
A、上限值或下限值
B、最大值或最小值
C、上限值或最大值
D、下限值或最小值
参考答案:B
Mr. Black ______ Shanghai in a few days. Do you know when the earliest plane ______
on Sunday? [ ]
A. is leaving, takes off
B. leaves, takes off
C. is leaving, is taking off
D. leaves, is taking off
设函数 在x=0处连续,则a=()