Helium is a very light gas.氦是一种非常轻的气体。A synthetic element produced in trace quantities by helium isotope bombardment of curium.锎一种合成元素,由氦同位素轰击锔可得到微量的这种元素.helium balloons for the children’s party儿童聚会用的氦气球Helium is a gas u...
Helium is a very light gas.氦是一种非常轻的气体。Helium is a gas used in balloons.氦是一种用于气球的气体.Unlike helium - 4, it cannot be produced by radioactive decay.与氦 - 4不同之处是, 氦-3不能由放射性衰变产生....