yesterday这个时间副词前面不加介词on、in。
yesterday
英 [ˈjestədeɪ] 美 [ˈjestərdeɪ]
adv.在昨天
n.昨天;不久前;近日;往昔
例句：They arrived yesterday.他们昨天到达。
I can remember our wedding as if it were yesterday.我们的婚礼我记忆犹新，就像昨天一样。
Where were you yesterday morning?你昨天上午在哪儿？
扩展资料：
1、今天 today
I've got a piano lesson later today.今天晚些时候我有一堂钢琴课。
The exams start a week today/today week (= one week from now) .考试于下周的今天开始。
2、前天 the day before yesterday
Perhaps the day before yesterday. 大概是前天吧。
