根据括号中所给的汉语写出单词，使句子意思完整正确。(每格1分，共5分)
My mother often _________ (购物) at weekends.
_______ (每个人) is here. Let’s begin our class.
The swimming pool is ________ (开放) from 12 a.m. to 8 p.m.
We go to the Computer Club three ________ (次) a week. We can learn a lot in the club.
----Is this the _________ (理由) why you are late for school today, Jim?
----Yes, it is.