美国是世界上的经济强国,20世纪90年代以来,美国的经济增长主要得益于  (    )

增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1).每处错误及其修改均仅限一词；

2).只允许修改10处，多者（从第11处起）不计分。

    When Joe left university,she got a good job in the bike factory.But after he had been worked there for some years,he decided to have a change,so he put a notice in several newspaper.It stated what experience he had and the kind of job he will like to have.One of the answers he received was about a man looking for a job,too.This man wrote to him,"Dear sir,when you get a new job,being kind enough to give my name or address to your present boss as I have beer trying to find a position like yours for a long time."After he read the letter,he sudden realized he had done was really foolish.

材料一：红地球葡萄粒大、色泽艳红、果肉脆硬、含糖量高，深受广大消费者青昧，近年来渭北黄土高原区形成了红地球葡萄专业产区。

材料二：渭河流域、渭河南北向基岩剖面和渭北红地球葡萄产区气象资料图。

从如图所示实验结果可以直接得出的结论是（　　）