In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each number.
Passage:

A dam is built across a river at sites where one can (1)........... a lot of water. This forms (2).............. reservoir and as the watercollects, it (3).............. vast areas of land. This is (4)............ the wall of the dam across the river is high and the (5)............ spreads over a large area.