设有关系R(S，D，M)，其函数依赖集F={S→D，D→M)，则关系R至多满足 ( )。
A．1NF
B．2NF
C．3NF
D．BCNF
参考答案：B
下列哪种术式术后发音功能最好（）。
A.声带切除术
B.喉垂直部分切除术
C.喉声门上水平部分切除术
D.喉水平垂直部分切除术
E.额侧切除术
They will pay a visit to Europe in a couple of years _____ they have enough money.
A．for fear that
B．on condition that
C．even though
D．as well as
