题目

All through his life, Einstein was ____ spend most of his time alone, although the married twice and had lots of close friends. A. content to   B. contented to   C. content with   D. contented with   答案：A下列说话完全正确的一组是（　　）①细胞分裂与细胞分化都能使细胞数目增多．②单细胞生物主要生活在水域环境里．③叶变成刺的仙人掌仍能进行光合作用．④生态系统不仅包括一定的环境，还包括其中的一些动物和植物．A．①②③B．②③C．①④D．③④