[mesmark]

I've got some students here who have a problem with L1 transfer. In Japanese, my students would say 'I went to a conference last week and *I could make some friends.'

I need to make a lesson plan that shows them when they should just use the plain past and when to use 'was/were able to ~', but first I need to understand why we don't say *'I could make some friends.'

Is it just that it's confusing with the subjunctive?
- If I went, I could make some new friends, but I have other plans.'

Is that just the way it is?