Peter McK, I agree that these sentences are pretty strange)) But it was exercise on the website.
So let's assume I have never used washing machine before (for example, I am a kid). I don't know how to operate a washing machine and how much detergent to put in the machine.
Or instead of doing laundry we can talk about cooking.
"I am a complete ignoramus in cooking"
"I am completely ignorant when it comes to cooking".
Will it be right?