大力植树造林，可以改善气候的原因是（ ）
①蒸腾作用旺盛，使大气湿度增加
②光合作用旺盛，改善氧气与二氧化碳的平衡
③呼吸作用旺盛，产生的水量增多
④可以保持水土，防风固沙．
A．①②④
B．①④
C．②③
D．①②③
绿色植物通过光合作用制造的有机物，不仅满足了自身的需要，而且是动物和人的食物来源以及多种工业原料的来源；光合作用储存在有机物中的能量，是植物自身和其他生物进行生命活动所必需的能量来源；光合作用释放氧气，不断消耗大气中的二氧化碳，维持了生物圈中碳-氧的相对平衡；同时，大力植树造林还可以为动物提供栖息地和生产环境，因此大力植树造林，可以改善环境的原因是①②④．
故选：A
| 阅读短文，从方框内所给的ABCDE中，选出恰当的一项还原到文中合适的位置，使文章意思完整。 | |||||
| We sometimes call the lion“the king of the jungle”because it is stronger and more dangerous than other animals. 1 It is the highest animal in the land food chain. In the sea, the shark is one of the animals at the top of the food chain. It can swim faster than most other sea animals. 2 3 People are! We are not the biggest or fastest, but we are the cleverest. We could not run faster than cheetahs, so we invented cars and now we can move the fastest. We could not fight better than lions, so we invented guns. Now we can hunt the best. People’s inventions are clever, but they can be dangerous, too. For example, people invented factories, and now they make the air and rivers dirty. 4 Dirty rivers kill fish, then bears cannot eat the fish and die. If we kill one part of the food chain, other parts also die. Rememberthat we are part of the food chain, so we are in danger, too! 5 We should and we could do something for the world!
1. 2. 3. 4. 5. |
