Analysis of test questions: the characteristics of rice planting in monsoon paddy field are: low mechanization level; High yield and low commodity rate; Small-scale operation, small scale; Low scientific and technological level; The amount of water conservancy projects is large. So choose D.
Comments: This question examines the characteristics of monsoon paddy field agriculture, which is less difficult. The key to solve the problem is to remember the characteristics of monsoon paddy field agriculture.