You arrive on scene when another lifeguard is performing cpr, what hould you do first?

Check the scene and and ask if they have gotten somebody to call 911 and/or AED, then ask if they need to take a break from CPR and take over if you’re certified

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.