i=1:j=30
m=(i+j)\2
Do While i < = j And key < > a(m)
If key >a(m) Then i = m+1 Else j = m-1
m=(i+j)\2 ①
Loop
数组元素a(1)到a(30)各不相同且按升序排列,若查找键key与a(9)相等,执行该程序段,①处语句的执行次数是( )