I know only too well that plans can go wrong.计划很容易出岔子，对此我太清楚了。I know only too well that plans can easily go wrong.计划很容易出岔子，我太清楚这点了。Even expert drivers can make mistakes.即使是熟练的驾驶员有时也会出岔子。That's a sure sign that something's gone astray.那个迹象明确表明有什么事出岔子了。