石料开始被用作盖屋顶的材料。Stone began to be used as a roofing material.这座雕像是用整块石料雕成的。The statue was carved out of a single piece of stone.大理石是一种珍贵的石料.Marble is a precious stone....
重返大气层的航天器受到重力的作用。Spacecraft which are re-entering the earth's atmosphere are affected by g forces.反射器通过支架牢牢地固定在航天器的侧面。The reflector is held onto the sides of the spacecraft with a frame.科学家密切跟踪航天器的运行.Scientists are ...