Furthermore, although(状语从句) it is commonly supposed that social gorups have a single leader,

research suggests(宾语从句) that there are typically two different leadership roles(定语从句) that are held by different individulas.

1.词汇短语

Furthermore :  而且，更深一层次的递进关系，一般放在句首

Furthermore, he cautioned against overplaying the potential impact of

                                                    interest rate rises and further big increases to the bank reserve requirement. 

                                                    此外，他还警告人们不要过分夸大加息和进一步大幅上调银行存款准备金率的潜在影响

it is (commonly) supposed that

social groups 社会团体

a single leader

different individulas

2. 语法 

although引导的状语从句  不能加but

后面的句子要是 对称结构

英语----托福阅读----长难句4