It’s never too early to 【B1】______ your skin—or your children’s—from the sun. The sun produces 【B2】______ rays—【B3】______ A(UVA)

It’s never too early to save your skin—or your children’s—from the sun. The sun produces invisible rays—ultraviolet A(UVA) and ultraviolet B(UVB) that can cause short- and long-term skin damage.
    The immediate effects of harmful sunrays—sunburn, photosensitive reactions, and cell and tissue damage—are bad enough. But medical experts believe that too much exposure to the sun in childhood or the sun in adolescence is a major cause of skin cancer and premature skin aging later in life. Health experts also believe that UVA may weaken the immune system.
    You can take steps early and often to minimize the sun’s harmful effects. Using sunscreens regularly on children, for example, can reduce their risk of skin damage later in life.
    Sunscreens provide some protection by blocking the sun’s rays on the skin. They are labeled with a sun protection factor(SPF): the higher the SPF, the greater the protection against harmful sun rays. But no sunscreen totally blocks the sun’s rays.