Our special thanks to go thousands of volunteers, without ____tireless work, none of this would be possible.

A．which

B．whom

C．whose

D．that

某港口重力式码头为条形基础，基底为抛石基床，厚度d₁＝2m，抛石基床底面处有效受压宽度B＇_e＝14m，抛石基床底面合力与垂线间的夹角δ＇＝11°，抛石基床底面以下土的抗剪强度指标标准值ψ_k＝24°，c_k＝5kPa，天然重度标准值γ_k＝18.0kN/m³，抛石基床厚度范围内土的重度标准值γ_k1＝19kN/m³，试计算地基极限承载力的竖向分力标准值（承载力系数N_r＝3.75，N_c＝12.47，N_q＝6.55）。