1·In some cases, no amount of herbicide has allowed farmers to gain control of weeds and farmland has had to be abandoned.
某些情况下，无论使用多少除草剂，农民也无法控制野草的疯长，这样的农田不得不放弃。
2·An analysis on the effect of cultivated grassland on soil respiration rate was conducted for the abandoned land and the transferred farmland in the Ordos Sandy land Improvement Experimental Station.
在鄂尔多斯沙地改良试验站的撂荒地和退耕地，测定和分析了多年生人工草地对土壤呼吸速率的影响。