However，at times this balance in nature is _______ resulting in a number of possibly unforeseen effects.

When we arrived in the deep night, we found there was no food _______ as all the shops were shut.

With the debt problem worsening, it is going to be a ______ test for EU to help Greece out of trouble.

The top of the hill is _________,but the trees grow part way up its slope.

In the middle of the room there is a ______ table, with eight chairs around it.