2 certain or safe; of a good standard; giving confidence or support -- 确定的;扎实的;可信赖的
3 continuing for a period of time without stopping -- 持续的,不间断的
4 an object that has a height, width, and length, and is not flat -- 立体;立体图形
5 a substance that is not liquid or gas -- 固体物质
The construction should be sturdy and solid.
This theory needs to be backed up with solid empirical data.