_______ with so much trouble, we failed to complete task on time.
As there is less and less coal and oil, scientists are exploring new ways of making use of ____ energy, such as sunlight, wind and water for power and fuel.
In the future, senior citizens will be able to go anywhere using high-tech cameras _______ to their head.
As he works in a remote area, he visits his parents only ______.
Don’t mention that at the beginning of the story, or it may _____ the shocking ending.
With two extra floors built, this hotel can ________ more people than before.