Answer:
The doctor wanted to know when I last took my temperature.
Step-by-step explanation:
Reported Speech or indirect speech uses the past tense & is commonly used when a person wants to convey what another person told without using it's direct form.
In direct speech, the person who conveys the message quotes the person in first person narrative & narrates by using the direct form.
There's a noticeable change of tense when you shift from reported to direct speech & vice versa.
Here's another example for you:
In direct speech: Tommy said, "Dave, did you know that Jane is coming back?"
In indirect speech: Tommy asked Dave if he knew that
Jane was coming back.
Here, we use past tense when we change to past tense (is - was, know - knew). We also change the narrative (you - he).