He usually sleeps for twelve hours every day. 他通常每天睡12个小时。

since 其后接表示"时间点"的短语或从句（过去时），也可以接"一段时间+ago"，常用于完成时态；还用于句型："It is +时间段+since+一般过去时的句子"。表示过去某个时间发生并持续到说话时的动作或状态。

　e.g. It is two years since I came to China. 自从我到中国以来已经两年了。

She has worked here for five years. =She has worked here since five years ago.

她在这儿工作5年了。

2. Jeff's family is having a yard sale.

sale用作名词，意为"出售，销售"，on sale意为"出售，上市"；for sale意为"待售，供出售"，尤指从主人手里出售。

　e.g. Chickens are on sale in the market.

小鸡在市场上出售。

I'm sorry, it's not for sale.

抱歉，它不出售。

3. Amy thinks it's hard to sell her old things.

　艾米认为卖掉她的旧东西很难。

It's +adj. (+for sb.) to do sth. 意为"（对某人来说）做某事时......的"，it 是形式主语，真正主语是后面的动词不定式。

　e.g. It's important for un to learn English well.

学好英语对于我们来说是很重要的。

4. Amy wants to keep her old things because they bring back sweet memories.

艾米想保留她的旧东西，因为它们勾起她的甜蜜回忆。

memory n. ，意为"记忆；回忆"，复数形式为memories，动词为memorize，意为"记忆，背诵"。

　e.g. She has a good memory. 她记忆力好。

5. I've had this magazine for a couple of months. 这本杂志我买了几个月了。

a couple of 表示具体的数量"两个"，指两个相同的人或物体; 表示数量不定的"少数几个"，作这种虚指的用法时，具体意思往往视上下文和具体的语境而决定，例如：

You have to wait for a couple of hours for the clothes to dry completely.