Learning during chazarat hashatz (the repetition of the amidah)

Hi,

One should not learn Torah during the repetition of the amidah. There are a few concerns:

1. At least 10 men must pay attention to every word of the amidah;

2. All of those who are present are obligated to pay attention to the end of each berachah and answer Amen;

3. Even if there are ten who pay attention to every word, and even if the one who is learning is careful to pay attention sufficiently to answer Amen, others may misunderstand and assume that all learning is permitted.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:19)

Have a great day,
Mordechai