题干

外太空是一个充满神秘和无限遐想的地方.乘宇宙飞船在太空长期航行中的宇航员,需要大量氧气的供应和生活粪便的有效分解.科学家设想在船舱中建立一个“小球藻﹣﹣腐生菌循环净化器”来解决这一问题.(小球藻是一种单细胞藻类植物).请回答下列问题:

(1)该循环净化器中必须为小球藻提供的原料是____ 和____ .

(2)必须为该循环净化器提供的外部条件是:____ .

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    “I never wanted to come on this stupid hiking trip!” Jeff's voice was panicked. His father stopped and turned to look at the boy.

    “This is hard on you, son. But you've got to come through with your courage.”

    “But I am scared!” Jeff shouted.

    “Please have enough love for your brother to think this through!” His father replied, “We just don't have the time to stop. And I don't know if I can make it without stopping every so often. While you're only ten, you're strong and fast. Do you remember the way back from here to the road, if you had to go alone?”

    Jeff flashed back to the painful scene of his seventeen-year-old brother Mark at their campsite. He'd been bitten by a snake during a rough hike. He needed medical attention right away. Worse still, their cell phone was dead.

    “Jeff? Could you make it to Flint without me? You can get help there.”

    Jeff nodded, said goodbye to his father and continued climbing over the rocks. The rocks and branches threatened his footing and speed, but stone by stone, he made his way up the valley.

    Jeff turned and made the final climbing-up toward the road. When he reached it, he rested himself, breathless. “Can't stop,” he thought. “Mark's in big trouble Keep going.” Just as he pulled himself upright, a truck sped by, heading for Flint " Hey!” he shouted excitedly, waving both arms. The truck stopped, "Jump in, boy! What's up? "The driver asked, Jeff got in and explained. Immediately the driver reached for his cell phone. “Help! Help! Better get the helicopter in there,” he seemed to be shouting into his hand. But Jeff wasn't sure about that because everything got unclear and then went black and quiet.

    Hours later, Jeff opened his eyes to find himself in a hospital, with his father nearby. His father told him that the helicopter airlifted Mark to the hospital and he would be fine in a few days. His father hiked himself out of that valley and took a ride from someone to the town. “You're a hero, son,” his father finally said with a smile.“ You saved Mark.”