They are all very clever, but _______of them could work the problem out.

 I found _________ hard to make myself understood by the old man.

_____________ worries me the way he keeps changing his mind. 

 ______ of the parents has confirmed it was their child’s fault to be late for class, saying the school bus came later than usual.

 —There is ______ milk in the fridge. Please buy some on your way home.—All right.