The completed conversation is:
Kid: I'm not ill, why are you giving me an injection?
Doctor: It's to protect you.
Here is a more detailed explanation of the grammar used in the conversation:
* The kid uses the contraction "I'm" for "I am".
* The kid uses the present continuous tense of the verb "to be" (am) to say that they are not ill now.
* The kid uses the present tense of the verb "to give" (give) to ask the doctor why they are giving them an injection.
* The doctor uses the present tense of the verb "to be" (is) to say that the injection is to protect the child.
I hope this helps!