— I have no idea about where to buy a present for my friend, can you give me some advi

You have no idea how worried I was.（英译中)

Which of the following italicized parts is a predicative clause（表语从句)？A．I have no idea

I have no idea______we met for the first time.A．thatB．whetherC．whatD．when

I have no idea who stole his wallet. It _____anyone.A. must have beenB. should have been

I have no idea（)to make my speech interesting.A. howB. whyC. when

I have no idea_________ they have kept in touch with me by E－mail since last year.A.what