如果删除了公式中使用的单元，则该单元显示（）。 ["###","？","#REF！","以上都不对"]
why should the SES operators be very careful when the ship enters the area where three ocean regions overlap? Because（）. ["the weather over there is always terrible","the condition there is complicated","the signals are too strong","their SES may receive the signals from unwanted satellite"]
什么是体积分数、质量分数？两者的关系如何？
尼龙带的抗拉力为（）。 ["5kN","10kN","15kN","20kN"]
采用打桩法人工地基时，应注意局部换土的新土应与周围土质接近，为什么？
预应力钢筋包括哪些？
