A river that rises in the Rocky Mountains of northern Colorado and flows southwest for 1,468 miles (2,333 km) to the Gulf of California. It passes through the Grand Canyon..

Piece of paper showing you have paid. mark bill as paid.

Machine (such as a car) used to carry things.

cause, explanation, or justification for action or event. Explanations for why some things occurred or was done. think, understand, and form judgements logically.

To turn something on.

To come back after being away from somewhere. To put, bring, take, give, or send something back.

Word such as 'a', 'an', or 'the' used before nouns. bind to undergo training period.

difficulty or problems. To worry, bother or disturb someone.

complex of runways and buildings for take-off, landing, and maintenance of civil aircraft.

on Wednesday. day of week before Thursday and following Tuesday.

using thought or rational judgement. Thoughts behind an idea, opinion or belief. To have an idea, opinion or belief about something.

gladly received. used to greet someone in polite or friendly way. Friendly greeting to someone who has arrived. greet someone arriving in polite or friendly way.

To take or go with someone to a place.

state of being anxious and troubled. Some things that causes trouble or concern. To cause concern or trouble over something.

Not present; not available. To fail to understand someone's message.