Not until he retired from teahcing three years ago ________ having a holiday abroad.
A.
he had considered
B.
had he considered
C.
he considered
D.
did he consider
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【简答题】已知梁的截面尺寸为b×h=250mm×450mm;受拉钢筋为4根直径为16mm的HRB335钢筋,f y =300N/mm 2 ,A s =804mm 2 ;箍筋采用 10;混凝土强度等级为C40,f t =1.71N/mm 2 ,f c =19.1N/mm 2 ;承受的弯矩M=89kN·m,环境类别为一类。验算此梁截面是否安全。