If we want to say that we are 95% sure that something happened, we use must he + past participle. We normally use should he + past participle to talk about criticism and regrets. For more information, see this guide to past modals. For practice, try this past modals practice activity.
Exhausting and exhausted are not interchangeable. We use exhausting to talk about the cause of the exhaustion, and we use exhausted to talk about the receiver of the exhaustion. This rule applies for words like boring/bored, interesting/interested, exciting/excited, terrifying/terrified, etc.
IncorrectIf we want to say that we are 95% sure that something happened, we use must he + past participle. We normally use should he + past participle to talk about criticism and regrets. For more information, see this guide to past modals. For practice, try this past modals practice activity.
Exhausting and exhausted are not interchangeable. We use exhausting to talk about the cause of the exhaustion, and we use exhausted to talk about the receiver of the exhaustion. This rule applies for words like boring/bored, interesting/interested, exciting/excited, terrifying/terrified, etc.