Carl said that if he is older than you, then you must be 16. Is this conjecture always true never true or sometimes true? • always true
• never true
• sometimes true

Plants can have a positive and negative effect on the rate of weathering

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

The african continent is home of the worlds largest desert and longest river . t or f