5. It is necessary to improve the packaging.

　　改进包装方法十分必要。

　　还能这样说：

　　Improving the packaging is necessary.

　　It is necessary to make the packing better.

　　应用解析：

　　improve abilities 提高能力;

　　improve one's time 善用时间;

　　improve in health 改善健康

　　6. We have a big demand for this product.

　　关于这类产品我们有很大的需求量。

　　还能这样说：

　　We need to a big deal of this product.

　　There is a great demand for this product.

　　应用解析：

　　have many demands on one's time 时间不够支配;

　　in great demand 需要量很大

　　7. Our toys are lacked variety.

　　我们的玩具太单一。

　　还能这样说：

　　Our toys are too simple.

　　We don't have various toys.

　　应用解析：

　　a variety of 各种各样的，种类繁多的;

　　every variety of form 各种形式

　　8. Manufactures are interested in technical improvements.

　　生产厂商对技术改进很感兴趣。

　　还能这样说：

　　Manufactures are fond of the technical improvements.

　　Manufactures take a great interest in improving the technology.

　　应用解析：

　　bear interest 产生利息;提供利息;

　　give back with interest 连利息一起偿还某人;加倍还击某人