Question 1 (b) (iii):-

This refers to a double dotted quaver and demisemiquaver, with a turn above them. The question asks what the two dots tell the player to do. I don't know how to describe it! One can't say that they tell the player to hold the note for however long because of the turn.

Any ideas?

The first dot adds half the value of the note and the second half the value of the first dot.

Forget the turn, concentrate on the dots in this case - it's only Grade 5 level. Add on three quarters of the value of the note to the note.