1. I said to her, "Are you fond of swimming?"
2. He asked her if she was fond of swimming.
3. He asked her if she 'is' fond of swimming.
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#1 can be changed into #2. What about #3? If we use 'is,' is it incorrect?
Both 2 and 3 are correct, but with slightly different meanings.
2 seems to be asking about how she felt in the past (which may or may not apply to the present).
3 is asking how she feels about swimming now -- at this time in her life.
When it comes to properly reporting speech, it is important to maintain the accuracy of the original statement. In this case, the original statement is "Are you fond of swimming?" So, when converting it into indirect speech, we need to use past tense verbs because the reported speech is being reported after the fact.
Both #2 and #3 are correct, as they follow the rules of indirect speech by using past tense verbs. However, there is a slight difference in meaning between the two.
In #2, the reported speech uses the past tense verb "was," which indicates that the question about being fond of swimming was asked in the past.
In #3, the reported speech uses the present tense verb "is," which implies that the person being asked about their fondness for swimming is still relevant at the time of reporting.
So, while both options are grammatically correct, the appropriate choice between #2 and #3 would depend on the intended meaning and context.