There is a store near my home. It is big. It has lots of things in it. You can buy school things like notebooks, pens, pencil cases, rulers and maps. You can also buy drinks, vegetables, fruit and all kinds of food. It doesn't sell clothes. Some of them are cheap. But some of them are expensive.

    People in the store are very friendly(友好的). They work from eight in the morning to eight in the evening. They work hard(努力地)all day.

在生态系统中，生物的种类、各种生物的____和____总是维持在相对稳定的状态，这种现象就叫做生态平衡．

2017年9月21日，复兴号正式提速，时速350公里载客运行。全长1318公里的京沪高铁线路，“复兴号”只用了4个半小时便跑完，跑出了世界高铁商业运营最高速，再次刷新“中国速度”。除了速度快，“复兴号”高平稳度也令人惊叹不已，笔与倒置的矿泉水瓶稳稳的竖立长达近十分钟。

在细胞有丝分裂的过程中，染色体、姐妹染色单体、DNA 分子的数目比为1∶2∶2，那么，该细胞所处的细胞分裂期是（ ）