单项选择题
A.select e.ename from emp e where exists（select x.empno from expense x where x.vouch_amt＞10000）and x.empno =e.empno；
B.select e.ename from emp e where exists（select x.empno from expense x where x.vouch_amt＞10000and x.empno =e.empno）；
C.select e.ename from emp e where x.empno =e.empno and exists（select x.empno from expense x where x.vouch_amt＞10000）
D.select e.ename from emp e，expense x where x.empno =e.empno and x.vouch_amt＞10000and exists（select x.empno from expense x where）
