鱼类的呼吸运动主要是依靠鳃盖拱起所引起的吸引力和口腔压缩所引起的压挤力产生。
查看答案
鳃丝上的横纹肌有节律的收缩可以起到“鳃心”的作用。
A. 对
B. 错
每个鳃弓上分布有两列鳃瓣,每列鳃瓣称半鳃。
A. 对
B. 错
According to the news, which of the following is true?[音频]
A. The month ofJanuary in Japan logged a record trade deficit.
B. The highest deficit in Japan is in 1979.
C. The highest deficit in Japan is in the 2008financial crisis.
D. The deficit in 1979 was 18.6 billion US dollars.
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