$(document).ready(function(){
bt1 = document.getElementById("lk1");                   
oc1 = document.getElementById("dv1");                   
bt2 = document.getElementById("lk2");                   
oc2 = document.getElementById("dv2");                   
bt3 = document.getElementById("lk3");                   
oc3 = document.getElementById("dv3");                   
bt4 = document.getElementById("lk4");                   
oc4 = document.getElementById("dv4");

$(bt1).click(function () {
$(oc1).toggle("normal");
});                                                     
                                                        
$(bt2).click(function () {                              
$(oc2).toggle("normal");
});                                                     
                                                        
$(bt3).click(function () {                              
$(oc3).toggle("normal");
});                                                     
                                                        
$(bt4).click(function () {                              
$(oc4).toggle("normal");
});

});