第23题:[单选题]A well-designed system should be( ).①easily understood②reliable③straightforward to implement④straightforward to maintain A.①② B.①③④ C.②③④ D.①②③④ 参考答案:D 题意为:一个好的设计模式应该是:easily understood:易于理解;Reliable:可靠的;straightforward to implement:易于实现的;straightforward to maintain:易于维护的。