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...
Scientists have found the bones of a hoofed grazing animal about the size of a small horse...科学家们已经发现了一种约有马驹般大小的有蹄草食性动物的骨骼。He was hoofed out of the Guards.他被开除出警卫队.Scientists have found the bones of a hoofed grazing anim...