A positive attitude is very important as it will make our life easier. In life, not everything goes as ____(smooth) as we want. There will be times when we will face problems and difficulties. The most ____(challenge) part is ____we react when we experience problems and difficulties.

    Instead of being discouraged, those who have a positive attitude ____ (treat) each failure as a lesson. And they will be inspired to achieve the goal.____those who do not have the positive attitude will see problems and difficulties ____ a different way. With different attitudes, the result will be quite different. Since every one of us ____ (possess) the same amount of time, why don't we just make the best ____the same amount of time with a positive attitude? Life itself is already hard. It will be much ____(good) if we have a positive attitude which will make our life happier and easier.

    If you learn to see the bright side of life when you ____(surround) by difficulties, you'll be building your positive attitude fast.

—Red.

研究者将大白鼠置于冰水中，以探究冰水对大白鼠生理功能的影响．

（1）大白鼠刚放入冰水中时出现战栗的现象，该反射的发生____ （填“需要”或“不需要”）大脑皮层的参与，属于____ （填“条件”或“非条件”）反射．

（2）冰水刺激大白鼠皮肤____ 产生兴奋，沿反射弧____ （填“单向”或“双向”）传导到骨骼肌引起战栗．

（3）冰水刺激还能引起____ （填激素名称）分泌增加，使代谢加快，以增加产热，产生热量的来源是____ （生理活动）．

（4）由此可见，大白鼠体温调节的方式是____ ．

（5）如图是在实验过程中，测得的兴奋传导时神经纤维上某点的膜电位变化示意图，该图中表示静息电位的是____ 点，B点过程的形成原因是____ ，C点表示____