✔ 最佳答案
A OLD MAN FELL ASLEEP UNDER THE TREE. (wrong)
AN OLD MAN FELL ASLEEP UNDER THE TREE. (right)
Use AN instead of A.
Reasons:
1- Use AN before the vowels (a, e, i, o, u)
2- Use A before the consonants (b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w, x, y, z)