a combined operation的用法和样例：
- The Effects Based Operations (EBO) concept is based on relating actions in a combined operations to overall effects.
- A combining operation returns a null reference (Nothing in Visual Basic) when the result of the operation is a delegate that does not reference at least one method.
- proceed by both land and water; conduct a combined operation by army and navy
- Give your baby a combined surname?
- Final development reveals a combined image.