超声波探伤只能检查出部件表面的缺陷，探测不出部件内部深处的缺陷。
参考答案：错
与98 g H3PO4所含有的氧原子数目相等的H2SO4是( )
A．98 g
B．49 g
C．1 mol
D．0.5 mol
He asked me for this book many times. Please tell him that he _____ have it tomorrow.
A．must
B．may
C．shall
D．both B and C
