He tried to________to cook a meal on the island but he failed.
After the bell rings, which indicates the ending of the exam, you_____ stay ____ you are until all your papers are collected.
Doing morning exercises _____ our health and we _____it.
The plan _____ by the Chinese government ____ rejuvenating the nation by relying on science.
---I apologized for_____ to tell you when and where the meeting will be held in advance.
Most birds find it safe to sleep in the trees, but _____ they have eggs or young chicks, they don’t use a nest.