未知题型 设有关系R、S和T如下图所示，则元组演算表达式{t|(u)((R(u)∨S(u))∧(v)(T(v)→(w)((R(w)∨S(w))∧W[1]=u[1]∧W[2]=∨[1]∧W[3]=∨[2])∧t[1]=u[l])}的运算结果是(48)。A．B．C．D．

多项选择题 仓管员应做好的记录有（）。

单项选择题 M: I thought you were going to call Jack this morning, before he left for work.W: How was I supposed to know he’d be leaving so early?Q: What does the woman imply?（）