She __________ play a joke on him in case he becomes angry.
—What do you think of the story? —Wonderful! It ______ my childhood.
______ life began on earth is one of the biggest puzzles that scientist found hard ______.
President Obama held talks with Chinese President Hu Jintao in Beijing, ________ economic recovery, climate change and stopping the spread of nuclear weapons.
The government has taken some measures to solve the shortage of electricity, but it may be some time ________ we have enough power.
A small plane crashed into a hillside five miles east of the city, ________ all four people on board.