英语必修三外研版module2同步精炼（4）及答案 module2 developing and developed countries period four grammar：link words[ 同步精练（外研版必修3，课标通用）时间：60分钟 ⅰ.用but，while，although或however填空 1．developing countries are those where agriculture is the main source of income，________this income is not enough to maintain a moderate level of living. 2．the birth rate in develop
