如图表示一交流电的电流随时间而变化的图象，此交变电流的有效值是（ ） A．5A

阅读理解。

     Most animals only have animals of a different kind for food. But sometimes two kinds of animals come

  together in a partnership (伙伴关系) which is good for them. You may have noticed some birds on the

 backs of sheep. This is not because they want a ride, but because they find easy food in the parasites (寄

 生虫) on sheep. The sheep let the birds do so because they can stop the parasites from troubling them.

 So though they can do with it by themselves, they can do better together with each other.

     Sometimes an animal has a plant partner. The relationship develops until the two partners cannot do

 without each other. This is so in corals (珊瑚) of the sea. Inside their bodies they have very small plants,

  which act as "cleaners", taking the useless things from the coral and giving oxygen in return. That is what

 the animal needs to live. If the plants are killed, or are even kept from receiving light so that they cannot

 live as usual, the corals will die.

1. Is the partnership between two animals good or bad for both sides?

    _____________________________

2. Can sheep stop the parasites from troubling them by themselves?

    _____________________________

3. Why do any birds like to sit on a sheep?

    _____________________________

4. What role(角色)do the small plants inside corals play?

    _____________________________

5. How do the small plants help corals?

    _____________________________

外国甲公司与中围乙公司共同投资设立丙中外合资经营企业。丙企业成立后，乙公司按照合同刊约定缴清了出资，但甲公司未能按照合同规定缴清出资。乙公司遂向甲公司发出催告函，要求甲公司在1个月内缴清出资，但1个月后甲公司仍未缴清出资。下列表述中，符合中外合资经营企业法律制度规定的有( )。

A．甲公司的行为视为放弁在合同中的一切权利，自动退出丙企业

B．乙公司应当在1个月内向原审批机关申请批准解散丙企业或者申请另找外国投资者承担甲公司在合同中的权利和义务

C．如果乙公司未在1个月内向原审批机关申请批准解散丙企业或者申请乃找外国投资者的，审批机关有权撤销对丙企业的批准证书

D．乙公司可以依法要求甲公司赔偿因其未缴清出资造成的经济损失

患者男性，50岁，排便时出血，量不多，肛门脱出肿物，表面色紫，微带白色，需用手推挤方能回纳，病已10年，近来加重。其诊断为：

A．直肠息肉

B．直肠脱垂

C．直肠癌

D．Ⅱ期内痔

E．Ⅲ期内痔

通过两个球面球心的直线叫透镜的______．

测量用互感器的主要作用（）

A.将高电压大电流变为低电压、小电流

B.将工作人员或测量仪表与高电压大电流隔离，保证人身和设备的安全

C.统一测量仪表的规格

D.扩大测量仪表的量程