[curious]

Hi, Mr P. I think Hela wants to ask you whether it is possible to use any tenses other than "future continuous" or "future perfect" in the main clause.
Let me try:

Present:
*1- By the time he arrives, we will have a meeting.
2- By the time he arrives, we will be having a meeting.
3- By the time he arrives, we will have had a meeting.

Past:
4- By the time he arrived, we were having a meeting.
5- By the time he arrived, we had already had a meeting.
*6- By the time we'd walked five miles, he was exhausted.

I can't think of any other sequence for the time being and I am not sure about 1 and I think it is also possible to use was, were and had in the main clause. Is it possible to use other tenses than simple present or simple past in the subordinate clause? By the way what does 6 mean? I find it hard to show it on the time line. Was he exhausted after or before we'd walked five miles? It was taken from Quirk. Thanks.