题目内容：

    A scientist locked himself in a small air-tight plastic tent with 200 plants to see if they could change CO2 into oxygen (氧气) fast enough to keep him alive.

Kurtis Baute locked himself in a 3m by 3m tent in his brother’s backyard in British Columbia, Canada. He hoped to find out if by surrounding himself with plants, the CO2 he breathed out could be changed into oxygen to allow him to survive in the locked tent for at least three days. Unfortunately, he had to give up the experiment after only 15 hours, as CO2 levels reached a dangerous point where he risked suffering brain damage.

“I could probably survive in the tent for three days,” Baute wrote on his website. “But my goal is not to just ‘not die’. My goal is to end this project without developing brain damage or just generally causing lasting harm to my body. But as it turns out, that’s exactly what he risked as the 200 plants he took with him into the tent couldn’t meet his needs. Clearly, a cloudy sky prevented them from receiving all the sunlight they needed to perform photosynthesis (光合作用), so they couldn’t recycle CO2 fast enough.

“Plants are great at taking in CO2 and they love it. Since it wasn’t a bright and sunny day, they weren’t getting the light they needed, which meant CO2 just kept rising. I had to give up the experiment as that continued.” the young experimenter said.

15 hours into the experiment, Baute reached the set danger point and then ended this experiment. Still, he called the experiment a “huge success” as his main goal was actually the terrible effects of climate change and CO2 emissions. “The conclusion about my experiment is that if CO2 is too high, I’ll escape, which is just everyday experiences for many people on this planet. Everyone deserves clean air, but not everyone has it,” he wrote.

1.Why did Kurtis Baute stay in the tent for only 15 hours?

A. The tent is too small for him to stay too long.

B. The environment in the tent is dangerous for him.

C. CO2 in the tent couldn’t be changed into oxygen.

D. He couldn’t survive in the locked tent any longer.

2.What made it hard for the 200 plants to satisfy Kurtis Baute’s needs?

A. His health condition. B. His wrong decision.

C. Too much CO2. D. The cloudy weather.

3.What does Kurtis think of the result of the experiment?

A. Disappointing. B. Surprising.

C. Satisfying. D. Interesting.

4.What may be the best title for the text?

A. A test to show the importance of clean air

B. Surviving in the tent

C. The set danger point

D. Making people know the use of plants