Problems relating to people's livelihood have been the focus of the government, especially _______

Premier Wen Jiabao included them in his government work report last year.[ ]

A. when  

B. if

C. until   

D. since

某建筑物中部屋面等截面挑梁∟(240mm×300mm)，如题图所示。屋面板传来活荷载标准值ρ_k=6.4kN/m，设计值ρ=8.96kN/m：屋面板传来静荷载和梁自重标准值g_k=16kN/m，设计值g=19.2kN/m。

根据《砌体结构设计规范》（GB50003—2001）抗倾覆要求，挑梁埋入砌体长度l₁，应满足下列（）项关系式。

A．l₁＞2.76m

B．l₁＞2.27m

C．l₁≥2.76m

D．l₁≥2.27m