使用Angular官方Demo时，下拉菜单没有数据

如题，官方的Demo中下拉菜单没有数据

js代码为：
angular.module(‘invoice1’, []).controller(‘InvoiceController’, function() {
this.qty = 1;
this.cost = 2;
this.inCurr = ‘EUR’;
this.currencies = [‘USD’, ‘EUR’, ‘CNY’];
this.usdToForeignRates = {
USD: 1,
EUR: 0.74,
CNY: 6.09
};

this.total = function total(outCurr) {  return this.convertCurrency(this.qty * this.cost, this.inCurr, outCurr);};this.convertCurrency = function convertCurrency(amount, inCurr, outCurr) {  return amount * this.usdToForeignRates[outCurr] * 1 / this.usdToForeignRates[inCurr];};this.pay = function pay() {  window.alert("谢谢！");};

});