What was the problem with using valves in computars?

What are The skeletal system of a frog and its function? Is there a particular part of the body mumps attack? Where does an aortic aneurysm happen? Is it normal for a teenage boy to have more female friends? What are some10 facts about the integumentary system? How do you naturally make your muscles smaller? What type of Lymph nodes are located along the sides of the neck? Does a running nose have anything to do with prostate cancer? When was Tinnitus Sanctus created? Why do some sources survive a longer period of time? Intra-aortic balloon pump papillary muscle rupture? Is there a lot of cholesterol in crablegs? What are the factors involved in the transmission of a nerve impulse? How does the paralysis of the cilia that line the airways that affect one's health? What responds to over inflation of the lungs? What systems do appendicitis effect? How does goblet cell protect the lungs? The prevents food or liquids from getting into the lungs.? What is pepticulcer? What role do the sphincter muscles play in digestion?