Two compression bars of the same material and flexibility,they（）
A. The critical stress must be equal, and the critical pressure may not be equal
B. The critical stress is not necessarily equal, and the critical pressure must be equal
C. The critical stress and pressure must be equal
D. Critical stress and pressure are not necessarily equal
The flexibility of the compression bar intensively reflects which factors of the compression bar will affect the critical stress.
A. Length, constraints, section size and shape
B. Material, length and constraints
C. Material, constraints, section size and shape
D. Material, length, section size and shape
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