D

    Imagine one day, the water taps in your house stop running. You have to buy water from shops. And still there isn't enough for everyone. Your mother has to save the family's shower water to do other things. Would you be able to stand that kind of life?

    Probably not. But that is what kids in Yemen are experiencing. Experts said Yemen is going to be the first country in the world to run out of water. According to a report, the capital, Sana, will run out of drinking water as early as 2025.

    Because of the shortage, the government often cuts the water supply. Hannan, an 18-year-old from Lahej, told the Times: "In a good week we'll have a water supply all week. But then the following week there will be water only for a day or two."

    Hannan said only rich people have enough water to use. They can buy water from the shops or from the water truck. Private companies own the trucks. They travel around the city every day to sell water – at very high prices.

    "A lot of people can't afford it," she said.

    The average person in Yemen uses 100 to 200 cubic meters of water per year. That is far below the international water poverty line （贫困线）of 1,000 cubic meters.

    The government is thinking of making use of seawater. But it will cost a lot and it may not happen soon enough to help the people of Yemen.

如图为真核细胞生物膜系统的简单概念图，请回答下列问题：

（1）A____ （填名称）为细胞的“边界”，其在功能上具有____ 性，因而可控制物质的进出．

（2）C所在的结构被比喻为细胞的大脑，这是因为它是____ 和____ 的控制中心．

（3）若用¹⁴C标记环境中的CO₂，一段时间后，发现D中首先出现¹⁴CO₂．则在D中膜结构上进行的过程是____，¹⁴C在D中的转移途径是¹⁴CO₂→　____ →（¹⁴CH₂O）

（4）F为细胞内最丰富的膜结构，在分泌蛋白的合成与分泌过程中，F产生的囊泡需转移至G并与之融合，G代表的细胞器是____ ，该过程体现了生物膜的结构特点____ ．

____

原始人类经历了从群居到聚族而居，从采集到种植，从狩猎到饲养家畜的演进过程。推动上述演进的主要因素是（　　）