（）提出了“雁行发展理论”。
A.库兹涅茨
B.弗农
C.赤松要
D.霍夫曼
参考答案：C
_______, and problem will be settled.
A．A bit more effort
B．making a little more effort
C．If you make a bit more effort
D．there being a little more effort
为了提高食品的货架期，应采用那些防腐保藏的方式？
