antony1995
I have never seen an aardvark, but last year my father did
this sentence is wrong due to the tense. The use of "did" is wrong, instead we should use "had" ... This can be explained in an easy way: ask yourself, "the father did what?" The Answer would be: the father "seen" an aardvard (as seen is given in the sentence). This clearly makes no sense.
Now let’s say the sentece was - "I have never seen an aardvark, but my father had seen one...." Here, whennyou ask yourself, "the father did what?" The answer is: "the father HAD SEEN an aardvard" which makes perfect sense.
You have to be careful as to what the tense of the action being used it, and if it matches with the tense used for the father. "the father seen" did not make sense, but "the father had seen" makes perfect sense.
I hope this helped you

This was a tricky one right here, easy to mess up