_____ in the garden for an hour, the girl suddenly realized she had forgot locking her car door.

A．Reading

B．To read

C．Having read

D．To have read

一冷杉方木压弯构件，承受压力设计值N=50×10³N，初始偏心距e₀=0，弯矩设计值M₀=2.5×10⁶N·mm，构件截面尺寸为120mm×150mm，构件长度l=2310mm，两端铰接，弯矩作用平面在150mm的方向上。

考虑轴心力和弯矩共同作用的折减系数φ_m，与下列何项数值最为接近（）.

A．0.421

B．0.449

C．0.509

D．0.425