阅读短文，下列问题

 B

    December 25 is Christmas Day(圣诞节). Christmas is an important holiday in many countries. OnChristmas Day, most families get together for a big dinner. They give presents to each other and visit friends. The Christmas tree is an important part of the Christmas holiday. Most families buy trees. The families decorate(装饰) the tree together. Parents usually tell their children that Father Christmas comes during the night and brings presents to good children. Of course, Father Christmas isn't real. The parents of the children are really“Father Christmas”. They put the presents under the tree or into their children's stocking(长统袜)after the children go to sleep.   

史料大致可以分为两类：一是直接的史料；二是间接的史料。凡是未经中间人手修改或转写的，是直接的史料；凡是已经中间人修改或转写的是间接史料。下列属于直接史料的是

从超市买来的新鲜蔬菜用保鲜袋装起来，可以延长储存的时间，其主要原因是（　　）

有一种感冒止咳药品的说明书上写着：“青少年每日用量80～120mg，分3～4次服用.”一次服用这种药品剂量的范围为 ____.