Here's how we can fix it and change "crew" to the past tense:
Corrected Sentence:
In the last stage, we launched an inflatable rescue boat and simulated rescuing an exhausted swimmer.
Here's the breakdown:
* "In the last stage" replaces "In last stage" for correct grammar.
* "we" is a more appropriate subject than "you" since we're talking about a rescue scenario.
* "launched" is the past tense of "launch," which is a more accurate verb for what happens with a rescue boat.
* "rescuing" is the present participle of "rescue" and is used to show the action of rescuing.
* "an exhausted swimmer" is the object of the verb "rescuing."
Now the sentence is grammatically correct and makes sense.