It's obvious that the experiment ______ a great success.
When a giraffe has ______ drink, it has to stand with its front legs wide apart in order to reach ______ water easily.
If we ___________some measures, we might have prevented the environmental pollution.
–May I smoke in the room? --No, you______________. It’s a non-smoking room..
---It’s a long time ______ I last saw you.---Yes, and it will be another month ______ we can meet again.
John received an invitation to dinner, and with his work ________, he gladly accepted it.