Make the following sentences shorter.

1) Embankment dams are constructed of materials dug out of the ground, including rocks, gravel, sand, silt, and clay.

2) Earth-fill dams are constructed by hauling the earth materials into place and compacting them layer upon layer with heavy rollers.

3) A large roller located horizontally between piers can be raised and lowered to allow ice and other materials to pass through the dam without much loss of reservoir water level.

 

Complete the following text with the words derived from the words in brackets.

Hoover dam is the _____ (high) concrete arch dam in the U.S., _____ (to build) on the Colorado River at the Arizona-Nevada _____ (to border).

It _____ (impoundment) Lake Mead. The dam, _____ (completion) in 1936, is _____ (to use) for flood and silt _____ (controlling), electric power, _____ (to irrigate), and domestic and industrial water _____ (to supply). It is 726 ft (221 m) high and 1,244 ft (379 m) long (along the crest), _____ (to have) a power capacity of 1,345 megawatts, and a volume of 4.4 million cu yd (3.36 million cu m).

Look at the table, fill in the blanks and fulfill the following tasks.