Show the next sentence to be recorded by the user when they log back in

Problem

At present, when a user logs back in, we show the sentence list from the beginning.
This will discourage users to record further, as it will be quite an annoyance to come back, navigate and find out where they left off, before contributing.
If we increase the sentence corpus, this will be much bigger problem of UX 🙂

Possible enhancement:

1. Always show a sentence to be recorded.
2. As a side feature, list the already recorded sentences separately.