/*
 * 获得焦点时
 * */
function sfour(a){
	var sd = a.value;
	if(sd == "Search products..."){
		a.value = "";
	}
}
/**
 * 失去焦点时
 */
function obour(a){
	var sd = a.value;
	if(sd == ""){
		a.value = "Search products...";
	}
}