材料技术指标
锰钢
铝合金
钛合金
碳纤维
性能(强度)
强
较弱
较强
密度(kg/m3)
7.9×103
3.0×103
4.5×103
1.6×103
—Yes, but it needs to go the clouds for hours.
DNA分子的基本骨架是( )
China is famous _____ the Great Wall.