salesforce VF page 显示 Dependent picklist field

public with sharing class locationController{

public list<location__c> locationList{get;set;}

public locationController(){
locationList = [Select ID, Country__c, State__c, City__c
From Location__c];
}

}

<apex:page controller="locationController">
Location Table
<apex:messages style="color:red"></apex:messages>

<apex:form>
<apex:pageblock>
<apex:pageblocktable value="{!locationList}" var="locItem">
<apex:column headervalue="Country">
<apex:inputfield value="{!locItem.Country__c}">
</apex:inputfield>
</apex:column>

<apex:column headervalue="State/Province">
<apex:inputfield value="{!locItem.State__c}">
</apex:inputfield>
</apex:column>

<apex:column headervalue="City">
<apex:inputfield value="{!locItem.City__c}">
</apex:inputfield>
</apex:column>
</apex:pageblocktable>
</apex:pageblock>
</apex:form>

</apex:page>