伴生种。
参考答案：
伴生种为群落的常见种类，它与优势种相伴存在，但不起主要作用。
瓦斯爆炸的氧气浓度必须达到（）。
Even though his friends like to ___ him,he never takes it seriously. [ ]
A. make up for
B. make out of
C. make fun of
D. make most of
