1. **Problem Statement:** List all intervals on which the given function is continuous, knowing it is discontinuous only at $x=0$ and $x=28$. 2. **Understanding Continuity:** A function is continuous on an interval if it has no breaks, jumps, or holes in that interval. 3. **Given Information:** The function is discontinuous at $x=0$ and $x=28$ only. 4. **Intervals of Continuity:** Since the function is continuous everywhere else in its domain except at these points, the intervals of continuity are all real numbers excluding $0$ and $28$. 5. **Expressing Intervals:** This means the function is continuous on the intervals: $$(-\infty, 0) \cup (0, 28) \cup (28, \infty)$$ 6. **Final Answer:** The function is continuous on $$(-\infty, 0) \cup (0, 28) \cup (28, \infty)$$.