从a、b、c、d四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。 例：to make members of a team perform better, the trainer first of all has to know their _____ and weaknesses． a．strengths b．benefits c．techniques d．values 答案：a 21．as the quality of the city’s air continues to give rise to ________, the residents are encouraged to set off fewer fireworks． a．concerns b．compromise c．descriptions d．emergency 22．the ________ in chinese exports in recent years has resulted in a flood of inexpensive goods for american consumers． a．immigration b．introduction c．explosion d．investment
