Each chasm shows a task in plain English above the terminal, plus a handful of sample strings on the planks below — some must match, some must not (look for the ✓ / ✕ badge above each one). Type a real regular expression and press Enter to test it — it runs for real against every sample. Get them all right and the bridge locks in so you cross; get any wrong and it costs you time. Use the Hint button if you get stuck — it costs 15 seconds. Cross every chasm before the clock runs out.