He thoroughly understood the society __________.
he teacher told them since light ________ (travel) faster than sound,lightning ________ (appear) to go before thunder.
新民主主义社会是 _______。
在新民主主义的五种经济成分中,属于过渡形式的经济成分是___________。
我国农业合作化过程中建立的初级农业生产合作社的性质是______。