设有如图2.20所示的关系R和S，写出下列元组演算表达式表示的关系。[img=349x182]17e2dc45df28841.png[/img](1)[tex=9.714x1.357]V12q+5vCcawawArkId85R3pbcLmJRxFVzzp918kz+f5qL7W9Knml7GIslb6dS4+Z[/tex](2)[tex=10.0x1.357]cuMEun721XJPf4SsEq9Xi6wEEyxc+3jK+ae3N946NeXb/yVWWFgf63PVLIpIJlbl[/tex](3)[tex=21.643x1.286]92awPMKnMsuMrQpxQyw0pp3UO/FQPy7zZLmXD5mJ4SzaXr57WkjIisB6IMMSZyr43PkivoaQRnTEVXZIT7NPZB4TAfjN8NkH6fR4U7QuToaa/EYHDZ3PedkdgLxHRLT3PKyCFfVyQ08KlPyOpcBjnA==[/tex](4)[tex=19.929x1.286]CLFrMfU/uZW5m9Jaf0W66rudn5h4RS2kaZwtl2Bl2P2v+jaru2atoFuahRicKyAZL1R7zaJ0Rk/BGjG3FDXrH+qMweTKUSclNXhYgeRulUTLkNN5BYPo55y/6ztEHgB7[/tex]