P6 Cloze 83 (Rio Grande)

The Rio Grande is one of the most important rivers in America although it is not the longest. However, (51) (a)   other significant rivers, it is not used for shipping.

In fact, oceangoing ships cannot (52) (a)   the waters.

Now, what makes the Rio Grande so (53) (a)   is its location. Since 1846, it has been the official border of Texas and Mexico.

The Rio Grande is (54) (a)   the fourth or fifth longest river system in North America.

It all (55) (a)   on how it is measured. This river twists so much that it occasionally changes course.

These course shifts can cause it to be longer or (56) (a)   . At its last official measure, the Rio Grande clocked in at 1,896 miles.

The river starts in Colorado and (57) (a)   downward to the Culf of Mexico.

Downward is the best way of describing it too. Not only does the river extend south, (58) (a)   it also starts in the mountains.

It gets lower and lower (59) (a)   altitude as it extends to the Gulf.

The Rio Grande today is mostly used as a (60) (a)   of drinking water.