How much gap should I take after a comma in a Reading passage?

A brief but noticeable pause is all you need for a comma in the Read-Aloud section, so that you don't sound like you're rushing through the sentence.

You may try reading the sample passage below aloud, and refer to this audio:

When the last fishing boat returned to the harbour each evening, old Mr Ng was always waiting. He had stood at the same spot on the jetty for forty years — not to fish, not to sell, but simply to watch. The men who worked the boats knew him well enough to nod, and he would nod back, and that was the entirety of their conversation. Some thought him lonely. He thought himself fortunate.

Common mistakes to avoid: reading too fast, swallowing word endings, running sentences together, a flat monotone throughout, or skipping words when uncertain of pronunciation (try your best guess instead).