lǎo / shī / jiě / shì / le / fǎ / yǔ / zì / mǔ / shàng / de / fù / jiā / fú / hào / yǒu / shén / me / zuò / yòng / 。老师解释了法语字母上的附加符号有什么作用。The teacher explained the function of the diacritical marks on French letters.