She had grown stronger and broader. It was difficult to recogniz

She had grown stronger and broader. It was difficult to recognize in this robust, motherly woman the slim, lively Natasha of former days, (compound sentence)
【正确答案】：She had grown stronger and broader, so it was difficult to recognize in this robust, motherly woman the slim, lively Natasha of former days
【题目解析】：两个或两个以上的简单句用并列连词连在一起构成的句子,叫做并列句,其基本结构是“简单句+并列连词+简单句”。并列连词有：and, but, or, so等。由于以上两个单句是因果关系，所以我们用so连接。