a ne'er-do-well lad的用法和样例：
- What a child should do, above all, is to do well in his studies.
- He will do well in that work because he has a lot on the ball.
- If you do well, you are accepted; if not, sin is a demon crouching at the door.
- You'd do well to take a leaf out of John's book.
- A humane society always does well by its old people.