the reason why i was alone in the mountains is that i had a difficulty with my guide.

是表语从句,用在be动词后面,这个从属连接词that只起连接作用,是无名英雄,在从句中不作任何成分,如：The problem is that I can't speak French.The problem is that I can't type *.但是在口语中把that常常省...there being nothing to do,we just talked on and on.独立主格 我要换成was，这句话还对吗？不考虑独立主格，光说句子 there was nothing to do,we just talked on and on. 这样对吗？不对，逗号是不能分隔两个独立的句子的，肯定是一句主句，另一句是从句，或者两句句子之间一定要加对等连接词so，如：There was nothing to do, so we just talked on and on.如果不加对等连接词，则一定用独立主格，希望我能帮助你解疑释惑。