问题
多项选择题
污泥消化，根据是否需氧可分为厌氧消化和好氧消化，( )。
A．厌氧消化可产生新能源
B．好氧消化可依靠自然充氧进行，不需对消化池曝气
C．好氧消化不能回收能源，运行费用高
D．好氧消化适合于小规模污泥的处理
答案
参考答案：A,C,D
解析：好氧消化池需要人工曝气，才能获得足够的溶解氧，保持好氧状态。
搜题请搜索小程序“爱下问搜题”
污泥消化，根据是否需氧可分为厌氧消化和好氧消化，( )。
A．厌氧消化可产生新能源
B．好氧消化可依靠自然充氧进行，不需对消化池曝气
C．好氧消化不能回收能源，运行费用高
D．好氧消化适合于小规模污泥的处理
参考答案：A,C,D
解析：好氧消化池需要人工曝气，才能获得足够的溶解氧，保持好氧状态。
One day, a boy found the cocoon(茧) of a butterfly and brought it home. A few days later, the boy saw a small 36 in the cocoon. He sat and watched for several hours as a butterfly struggled to make 37 body through that little hole. Suddenly it stopped. So the boy 38 to help the butterfly, thinking the butterfly might be 39 .He took a pair of scissors and cut the hole 40 .The butterfly came out of the cocoon but it 41 a little different. It had a weak body and small, thin 42 .The butterfly didn’t start to fly. In fact, the butterfly spent the rest of its life crawling(爬行) around with a weak body and thin wings. It was never able to fly. The boy acted with 43 but he didn’t understand why it could be like this. When a butterfly crawls out of the cocoon, it must struggle. The hard work of 44 out of the cocoon makes the fluid(液体) from the butterfly’s body into its wings. It helps the butterfly be 45 to fly. If the butterfly never has to squeeze(挤压) itself out of the cocoon, its wings will never get the fluid and it can never fly. 46 struggles are what we need in our lives. If we lived our lives without any problems, we would never learn or grow. We would not be 47 we could have been and we would never fly. In our lives, pain and suffering is the key to all windows, and sometimes even 48 growth, without it , there’s no way of life. We can’t avoid 49 or problems. So, next time you are 50 a problem or difficulty, remember the butterfly. Struggle a little—then fly!
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