单项选择题
图示应力状态的三个主应力是()。
A.98.84MPa,-98.94MPa,-100MPaB.78.84MPa,-88.94MPa,-100MPaC.98.84MPa,-88.94MPa,-100MPaD.98.84MPa,-88.94MPa,-200MPa
A.78.86MPaB.68.86MPaC.88.86MPaD.98.86MPa
A.80MPa,0,-20MPaB.20MPa,0,-80MPaC.0,-20MPa,-80MPaD.0,0,-80MPa