A.碰傷B.劃痕C.脫漆D.銹蝕
A.斜距B.水平距C.高差D.返回信號(hào)
A.鋼尺本身的尺長(zhǎng)誤差B.鋼尺在兩點(diǎn)間無(wú)支托C.室外氣溫為20℃D.兩點(diǎn)間坡度較大