most children nowadays are the only chidren they tend to be more self-centered．A. Ever s

问题补充：

most children nowadays are the only chidren, they tend to be more self-centered．

A. Ever since

B. Now that

C. Only if

D. Even though

答案：

A. Ever since

(答案→)B. Now that

C. Only if

D. Even though

解析：短语辨析。 A．从那时到现在 B．既然；由于 C．只要……就 D．虽然；即使。句意：由于当今大部分孩子都是一个，他们更倾向于以自我为中心。故选B。