java - 如何从生成的自动完成列表中选择第一个元素？

Question

代码是-

selenium.click("id=j_idt743:j_idt2340:lnkpgPtMHXProblemShowAdd");
selenium.focus("id=j_idt743:j_idt2340:txtPtMHXProblemPastMedicalHistoryName"); 
selenium.type("id=j_idt743:j_idt2340:txtPtMHXProblemPastMedicalHistoryName",s1);
selenium.typeKeys("id=j_idt743:j_idt2340:txtPtMHXProblemPastMedicalHistoryName",s1);
selenium.keyDown("id=j_idt743:j_idt2340:txtPtMHXProblemPastMedicalHistoryName","\40");
selenium.keyDown("id=j_idt743:j_idt2340:txtPtMHXProblemPastMedicalHistoryName","\13"); 

关键事件不起作用.......