In 1957, the Soviets launched Sputnik 1 into outer space.1957年，苏联人将“斯普特尼克1号”人造卫星送入了外层空间。It is the Sputnik and is ignored at our peril.其现实意义不亚于苏联当时发射首颗人造卫星,对此视而不见是非常危险的.Explorer One went into a higher orbit than either Sp...
For use with backflow preventer test cocks to protect from damage.用于防回流阀测试旋塞,防止受到破坏.Backflow preventer manufactured from 300 Series stainless steel for corrosion resistance.防回流阀采用耐腐蚀的300系列不锈钢制造.However, backflow may now ...