—I’m sorry I stepped outside for a smoke. I was very tired. —There is no______ for this while you are on duty. 

The most important _____ of his speech at the G20 summit was that we should all unite to fight against the financial．

Nowadays senior high students are burdened with too many        ，which is making them less and less confident.

Future will be a marvelous world of artificial ______----- robots might have their emotions and we human beings might have robots as friends．

The rocks are very big with _____ of colors on them.