Answer: Four pulmonary veins.
Explanation: Oxygen and nutrient rich blood will flow from the lungs back into this part called the left atrium (Or as some will call it, the left upper chamber in the heart). From there, it goes through four pulmonary veins.
Hope I could help! :)
 
        
             
        
        
        
Answer:
70 decibels and above can cause damage if heard for a long time
120 decibels and above is considered an immediate threat
Explanation: