Or is it one of the prize rocky planets that's mostly heavier, more dense material?

还是说它是一颗质量更重，密度更大的岩质行星？

Porcelain is a hard, white substance made by heating clay, a kind of heavy, sticky material.

瓷器是通过加热黏土制成的一种白色坚硬物质 ，黏土是一种黏性很大的原料。

Road maintenance work was very difficult, because the maintenance workers can only transfer heavy materials on their shoulders.

养护只有通过人力来进行，运输材料也只能靠肩挑背扛，养护起来特别困难而且特别辛苦。

New rockets usually carry blocks of steel or other heavy material instead of true cargo.

新火箭通常携带钢块或其他重材料而不是真正的货物。

He proposed swapping an internal grid of steel beams for a steel and concrete exoskeleton that would make buildings more resilient to wind while using far less heavy materials.

他提议将钢梁内部网格换成钢筋混凝土外骨骼，这将使建筑物更能抵御风，同时使用更轻的材料。

Japanese robotics and automation provider FANUC created the monster machine, as the company saw a need to increase the efficiency of the handling process of heavy materials for a variety of manufacturing industries.

日本机器人和自动化供应商 FANUC 创造了这台怪物机器，因为该公司看到需要提高各种制造行业重型材料处理过程的效率。

It means that you had better choose some light material rather than the heavy material as your packaging material so that it is easier to deliver; but at the same time safety must be taken into account, too.

意思就是说比起厚重的材料来，你最好选用轻薄的材料来包装商品，这样一来的话运输就会比较方便快捷。但是同时安全性也必须选用结实的材料并且要采取一些措施来保证物品不被损坏。