1 at the greengrocer's, 2 at school, 3 at the stationer's(在文具店), 4 at the hairdresser's, 5 at home, 6 on the dairy (farm), 7 at the grocer's 8 at the butcher's, 9 in the office, 10 at the baker's 11 in church, 12 on the weekend.

1 介词, 我在家, I am at home, 这个在/at就是介词;

2 动词, 我吃饭, I am eating, 这个吃/eat就是动词;

3 冠词, a, an, the三个, I am a girl, 我是个女孩, 这个个/a就是不定冠词, on the weekend, 在周末, 里面的the就是定冠词, 特指. the rich, 富人, the是定冠词.

4 be, 过去式有was/were. I was a worker, 我曾经是名工人. was就是be的过去式, 用于过去时中.

多看看语法书吧, 尤其是多看例句培养语感, 不然你的英语提高起来很慢. good luck.