Jim thought（that省略了）【D having】 conversations with friends was not helpful at all
that 引导宾语从句,做thought的宾语,可以省略.分析宾语从句的句子成分.
【 having】 conversations with friends 主语
was not 系动词
helpful 表语
at all 状语
所以动名词做主语,ABC都是动词,只能做谓语
无疑后请采纳.
书山有路勤为径,学海无涯苦作舟.
-----------与君共勉-----------