I think at this stage just relax, really all the hard has already been done, most often on the day things just come together and DC can surprise us. Believe it or not most children struggle with the comprehension, unless of course they are competent avid readers of many years, and even then that can still be the case. My DS finds comprehension difficult too, despite my prolonged ongoing attempts to correct this, by just ploughing through various types. I'm just not going to worry unduly, and just hope that a piece he gets to grips with appears on the day. Just get DC to do a paper a day until the exam, mark it, then get them to reread the text to you, then you read text to them, (yes I know very long process) then get them to answer questions again that they got wrong, then if they still don't get it offer explanations and answers at the end. Any other solutions with comprehension would be very interesting. Good luck!
Well put. I find exactly the same for my son. He's been doing pretty tough comprehensions (all inference questions) for a while and marks range from 68% to 90% for no obvious reason other than some he just gets quite well and some he doesn't - and when I go through them I find I am the same, with some I am struggling to answer and others seem easy. Hopefully the one on the day will be one that clicks with him!