理论上爆炸最强烈的甲烷浓度为9.5%,实际为8.5%。()
参考答案:错
It is said that sandstorms will become more __________ as a result of global warming.[ ]
A. frequent
B. normal
C. formal
D. rare
植物细胞的基本结构包括()和原生质体两大部分。