1.the letter w
1.The Obama Administration has pledged to double U. S. exports over the next few years as a way to cut high unemployment.
奥巴马政府已经承诺要在今后几年里让美国的出口翻一番，一次作为降低高失业率的一个途径。
2.A mathematical model for calculating soil temperature around double U-type buried tube heat exchanger is constructed.
建立了计算地埋管换热器周围土壤温度的数学模型。
3.Vertical heat exchanger is mainly pided into single U-tube heat exchanger and double U-tube heat exchanger.
垂直U型管换热器主要分为两种：单U型管换热器和双U型管换热器。
4.President Barack Obama's pledge to double U. S. exports in five years will further expand the need.
奥巴马总统承诺在五年内加倍美国的出口量，这将继续扩大这一需求。
5.The pact gives a lift to Mr. Obama's efforts to double U. S. exports by 2015.
该协定可为奥巴马2015年欲将美国出口增加一倍的努力提供助力。
6.Dynamic Analysis on Double U-shaped Aqueduct Structure
大型U形双渡槽结构动力分析
7.A heat transfer model for double U-tube geothermal heat exchangers
双U型埋管地热换热器的传热模型