时效热处理的主要作用是消除内应力。( )
参考答案:对
According to the principle of CRC calculation, given a frame-bit series M=11100111 and the multiple-term formula, frame-bit series generated by the CRC G=110011, then the CRC is
A.111101
B.00011
C.11010011
D.1101001
特殊运算符“IS NULL”用于指定一个字段为( )。
A.空值 B.空字符串C.缺省值 D.特殊值