25．保护和利用森林资源的最佳方案是

A．封山育林                                                 B．有计划地合理砍伐与种植

C．营造单纯林种                                           D．过度砍伐

将右边的疾病与相应的病因用线段连接起来

①巨人症                                              A 脑血栓

②近视眼                                              B 幼年甲状腺激素分泌不足

③传导性耳聋                                       C 视神经细胞受损

④一侧肢体不能活动                             D 幼年生长激素分泌过多

⑤失明                                                  E 鼓膜受损

⑥呆小症                                              F 晶状体过凸

⑦夜盲症                                              G 感染HIV病毒

⑧艾滋病                                              H 食物中缺乏维生素A