open-and-shut

详细解释:a. 极简单的, 明白的, 容易解决的, 时晴时阴的

英语解释：

形容词 open-and-shut:

so obvious as to be easily solved or decided

例句：

As far as I can see the whole matter is open-and-shut.我看整件事是一清二楚。