Question

Her ____second thing is to do her homework.横线部分为什么不用定冠词the

Answer 1

因为它前面有物主代词.

不用冠词的序数词：

a. 序数词前有物主代词时. his first visit to Beijing .

b. 序数词作副词.例如：He came first in the race.

c. 在固定词组中,如 at（the）first, first of all, from first to last等.