The disaster-stricken village was inaccessible _______ by helicopter, and the storm added to the rescuers’ difficulty.
Was it _____he said or something that he did _____ made her cry so sadly?
---I’d like to buy this book, dad.---Sorry, my darling, but the book is _____ adults only.
The two girls are so alike that strangers find ______ difficult to tell them apart.
He is busy now, otherwise he ______ go with you for a walk.
Having a trip abroad is certainly good for the old couple, but it remains _____ whether they will enjoy it.