These classes are distinguished by the terminations.
The first class ends in a, e, i, o, u, pronounced exactly as the Italian.
The second, in ai, ei, iei, oi, ui.
The third, in ar, er, ir, or, ur, air, &c.
The fourth, in an, en, in, &c.
The fifth, in ang, eng, ing, &c.
The sixth, in ak, ek, ik, &c.
The seventh, in as, es, is, &c.
The eighth, in at, et, it, &c.
The ninth, in ap, ep, ip, &c.