Ruth listened and started nervously at every passing footstep.露丝谛听着,每次有脚步声过去她就心惊肉跳.I listened for a footstep.我留心听着脚步声.The store is just a footstep away.那爿店仅一步之遥....
We tried to grow some copper sulphate crystals with our children.我们想跟孩子们一起制作硫酸铜晶体。Adding sulphate to the solution will give a precipitate.将硫酸盐加入该溶液会产生沉淀.More ammonium sulphate solution is being recovered in the process o...