Which of the following characteristics will increase the construction cost（）
A. Good airtightness and water tightness
B. Weak fire resistance
C. High strength and low weight
D. Brittle fracture tendency under some states
For the tension test of carbon steel, which of the following values is the highest（）
A. Yield stress
B. Tensile strength
C. Proportional limit
D. Elastic limit
CAD的英文全称是（）
A. Computer Aided Drawing
B. Computer Aided Plan
Computer Aided Graphics
D. Computer Aided DeSign
Which of the following are characteristics of the steel structure（）
A. High strength and low weight
B. Good plasticity and toughness
C. Easy to manufacture and construct
D. Weak corrosion resistance
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