题目

With the popular low-carbon lifestyle, energy saving occurs more frequently in everyday life. Here are a number of easy suggestions you can follow to keep cool without an air conditioner. Most don’t need electricity as well. 1.       Wet your wrists and other pulse points with cold water. Use a piece of ice wrapped in a face cloth. Constantly cooling off the wrists will also cool off the body. Never use just ice; make sure it is wrapped in a towel or something similar. Studies show that this will reduce your core body temperature by as much as 3.5℃. The relief is almost imm化简：tan（18°-x）tan（12°+x）+3[tan（18°-x）+tan（12°+x）]得（　　） A、0B、1C、33D、3