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1·Before, many teaching methods were used in English listening class, such as bottom-up or topdown, but the effect was not ideal.

以往，英语听力课教学虽采用了很多方法，如“自下而上”或“自上而下”的方法，但效果并不理想。

2·The application of dual-purpose pile in topdown construction can not only save costs, but also make the mechanic condition of substructure walls more rational.

在盖挖逆作法施工中采用“一桩两用”技术，不仅可节约大量费用，而且使地下结构的外墙的受力状态更为合理。

3·On analysis of the principle and application mode of des, a des module which fits for embedded security system such as IC card is realized by topdown design methods.

在详细分析DES的基本原理和应用模式的基础上，结合DES硬件实现的特点，采用正向设计的方法实现了适用于IC卡等有嵌入式安全需要的系统中的DES模块。