研究发现背向的电子发射产额不满足余弦关系，这是由于H2 +上的价电子所引起的。
The results show that backward electron emission yield deviates from inverse cosine law, due to the role of the valence electrons of H2 +.
我们的房子背向河流。
铅球完整技术教学中，背向滑步技术是铅球投掷的重要而复杂的教学环节。
In integrated technical teaching of shot, backsliding technique is important and complicated in the shot teaching.
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