WHAT IS THIS PASSAGE MAINLY ABOUT
1. What is this passage mainly about?
A. The importance of the Earth’s oxygen supply
B. Humankind’s effect on the environment
C. The survival strategies of tree populations
D. Dangers facing the Earth’s trees
1. What is this passage mainly about?
A. The importance of the Earth’s oxygen supply
B. Humankind’s effect on the environment
C. The survival strategies of tree populations
D. Dangers facing the Earth’s trees