【单选题】下列表示热轧带肋钢筋的强度等级符号的是( )
【判断题】钢筋符号HRB400表示的意思是:普通轧热带肋钢筋强度级别为400MPa。
【单选题】Grey whales have long been __________ in the north Atlantic and hunting was an important cause for that.
【简答题】热轧钢筋是低碳钢或普通低合金钢在______轧制而成。按照其强度的高低,分为______、______、______等几种,在图纸与计算书中分别用符号______、______及______表示,其中______钢筋为光圆钢筋,其余的为带肋钢筋。
【判断题】在配线子系统中,缆线既可以用正确绞电缆也可以用光缆。
【判断题】钢筋符号HRBF335表示的意思是:有抗震性能的普通热轧带肋钢筋强度级别为335MPa。
【判断题】在配线子系统电)缆线既可以用对绞电缆也可以用光缆。
【简答题】Every year thousands of grey whales make the longest migration of any animal, traveling 7,000 miles each way between the Arctic and Baja, California. The grey whales spend the long summer days in thei...
【单选题】Many species of whales will not breed unless ______.
A.
they are in the same group for a long term
B.
they are isolated from other species
C.
they are in the company of many other whales
D.
there are enough genes available