Throughout history man has changed his physical environment in order to improve his way of life. (1)________ the tools of technology he has altered many physical features of the earth. He has transformed woodlands and prairies（大草原）(2)________ farms and made lakes and reserviors（水库）out of rivers for irrigation purposes or hydroelectric power. Man has also modified （修改） the face of the earth by draining marshes (沼泽) and cutting through mountains to build roads and railways.
