As there is less coal and oil, scientists are exploring new ways of making use of _____ energy, such as sunlight, wind, and water for power and fuel.
David is such a good boy _______ all the teachers like him.
______ is mentioned above that the number of the students in senior school is increasing.
______ is mentioned above, the number of the students in senior school is increasing.
_______ is known to everybody that the moon travels round the earth once every month.
_____ is known to everybody, the moon travels round the earth once every month.