不知道你这句话是要表达过去时还是过去进行时呢.
如果是过去时,那么答案就是：
I read a book on Monday.
I drew a picture on Wednesday.
如果是过去进行时,那么答案就是：
I was reading a book on Monday.
I was drawing a picture on Wednesday.
从你给的句子上看,应该是已经发生过的动作了.所以选择这两种时态.