南方地区农作物可以一年两熟到三熟,主要原因是 [ ]
A.降水丰富
B.平原面积广大,河流多
C.土壤肥沃,水源充足
D.热量充足,高温期长
答案:D
根据我国环境标准管理的有关规定,省级人民政府可组织制定()。
A.环境基础标准
B.监测方法标准
C.污染物排放标准
D.环境质量标准
Mary made coffee ________ her guests were finishing their meal.[ ]
A. so that
B. although
C. while
D. as if