题干

在生态系统中有关食物链与能量流动的叙述,不正确的是(    )

A:能量沿食物链流动是单向的

B:食物链越长,最高营养级上获得的能量越少

C:一般而言,食物链中细菌的数量是最多的,其次是生产者

D:生态系统中的生物种类越多,食物链越多,食物网越复杂

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答案(点此获取答案解析)

C

同类题1

阅读理解

D

    “Volunteering makes you look at the world differently. You see how little things can change a person's life for the better, which makes everyone a better person.” Mason, a volunteer said.

    National Volunteer Week started in 1974 and is held every April. It is a time to thank volunteers for their achievements. It is also a perfect opportunity (机会) to encourage others to take their first step toward becoming a volunteer. Making the decision to take the first step can be the biggest problem, because they often wonder if they will be able to meet the organization's expectations (期望). Some people fear not knowing anyone else in the group. Not having enough time also prevents some from sharing their abilities.

    The following tips can help if you have some of these worries.

    ★Start out slowly, don't add too much pressure. Even a few hours a month can make a big difference in someone's life.

    ★Choose an organization with the same interests and common values.

    ★Take part in a training meeting for new volunteers, even if it is not asked.

    ★Work with a veteran volunteer. He volunteered a lot, he can help you increase the confidence and completely understand the organization's expectations.

    ★Invite a friend or family member to serve. It is a good experience to volunteer with them.

    ★Finally, it is most important to enjoy the volunteer experience and to remember that not all volunteer experiences are perfect. If one experience doesn't work, don't give up and you'll surely find the right opportunity.

    Spend some time on volunteer work and you will see great changes in people's lives. As Mason discovered during his volunteer experience, “…little things can change a person's life.”