Near Ellewoutsdijk you are driving at 80 km/h behind a tractor doing 60 km/h and want to overtake after only briefly checking your left exterior mirror. Is that enough?
Yes, the interior mirror and left exterior mirror together already cover everything
No, you must also look over your left shoulder to cover the blind spot
Explanation
Wrong — trap: final check step skipped. Only the look over the left shoulder covers the blind spot that no mirror shows (Book p.143).