Valves in veins are formed of the tunica media. cause venous blood flow to go in only one direction. are found only in the largest veins. make the use of a skeletal muscle pump unnecessary for venous blood flow. are the leading cause of high blood pressure.

the answer is trees if i'm not mistaken

the answer is admiramos

the rule for verbs is whoever you are referring to (in this case 'nosotros'), you need to change the ending of the word.

nosotros - amos

yo - o

tu - as

el, ella, usted - a

ellos, ellas, ustedes - an

(examples: nosotros bailamos (instead of bailar) or yo hablo (instead of habla)

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explanation: ill you out, join

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.