根据搜索结果，合并两句话时需根据逻辑关系选择关联词，以下是具体方法及示例：

一、关联词分类及用法

并列关系

表示平等或对等关系，如“and（和）”“but（但是）”“既……又……”

示例：My favorite colors are blue and green, but my sister prefers pink.

转折关系

表示对立或矛盾，如“although（虽然）”“however（然而）”“却……”

示例：Although it was raining heavily, we decided to go for a walk.

因果关系

表示原因与结果，如“because（因为）”“so（所以）”“既然……就……”

示例：I can't go to the party because I have to work overtime tonight.

条件关系

表示前提与结果，如“if（如果）”“only（只有）”

示例：If you study hard, you will pass the exam.

递进关系

表示程度加深，如“not only……but also……”“既……又……”

示例：She is not only intelligent but also very kind.

二、合并示例

转折关系

原句：The weather was bad. We still went out.

合并后：Although the weather was bad, we still went out.

因果关系

原句：He is poor. He helps others.

合并后：He is poor, but he helps others.

并列关系

原句：I like reading. I like writing.

合并后：I like reading and writing.

三、注意事项

选择关联词时需结合语境，确保逻辑连贯。- 避免滥用关联词，保持句子简洁明了。