$\frac{1}{2}$ 的倒数与0.25的倒数的积是____。

假如你穿越时空来到盛唐时期不可能经历的事情是（    ）

发烧是体温高出了正常范围，病菌、病毒感染是导致发烧的常见原因．请回答下列问题：

（1）大多数病原体进入人体内，经过____ 等的摄取和处理，暴露出其特有的____，引起人体产生特异性免疫．与此同时，某些免疫细胞还会产生白细胞介素等物质，随血液运输，作用于____ 的体温调节中枢，使机体的____ 等器官产热增多，同时____ 分泌减少、____ 收缩，散热减少，导致体温升高．

（2）通过对上述发烧过程的分析，说明人体维持内环境稳态的调节能力是____ ．目前普遍认为，____ 调节网络是机体维持稳态的主要调节机制．

下列各项中，与动物行为的形成无关的是（ ）

D

    It's summer now and the weather is getting hotter. You are thirsty playing basketball or riding home from school. A cold drink may be just the thing. There are plenty of "energy drinks" on the market. Most of them have beautiful colors and cool names. The lists on them tell you they are helpful to your health. Sounds great! But be careful what you are drinking. Something that looks cool may not be good for your health.

    After a careful check you may find that most energy drinks have lots of caffeine (咖啡因) in them. These drinks are especially aimed at ( 以…..为目标) young people, students, busy people and sports players. Makers sometimes say their drinks make you better at sports and can keep you awake.  But be careful not to drink too much.

    Caffeine makes your heart beat fast. Because of this, the International Olympic Committee has limited (限制) its use. Caffeine in most energy drinks is at least as strong as that in a cup of coffee or tea. Possible health dangers have something to do with energy drinks. Just one box of energy drink can make you nervous, have difficulty sleeping and can even cause heart problems. Scientists say that teenagers should be discouraged from taking drinks with a lot of caffeine in them.

根据短文内容，选择最佳的答案。