I could tell he was surprised from the ________ on his face. 

It is a fact that there is a     towards regional cooperation.

——-Shall we go out for a walk?——Sorry. This is not the right ____ to invite me. I am too tired to walk.

Measures _____to stop housing prices from rising too fast, but it remains to be seen whether they still work.

It’s really a(n)         that Tony, a child of only two, can play the piano so well.