英文改错～～～求助！！！

The first night we placed an arm-chair against the door and piled our bags on it.

Around one o'clock there was a knock on the door.

arm-chair 前面缺少冠词 +an

had改为was there be 表示有~· 不能也have混着用

At the first night,we put an arm-chair against the door and piled our bags on it.there came a rat-a-tat on the door around 1:00.

At the first night,we placed an arm-chair against the door and piled our bags on it.
Around one o'clock,there was a knock on the door.
上面的那个an要看你的具体情况,如果你有很多这样的东西,不特指,就用an,如果你是只有一个,或者这个东西在前面出现过,是一个别人都知道的东西了,就用the表特指