与情绪一样，我们的情感也是复杂的。当我们看到有人丢了东西却未发觉的时候，会好心上前提醒，这是（    ）

已知a，b，c为正数，满足如下两个条件：

a+b+c=32  ①   ② 是否存在以 ， ， 为三边长的三角形？如果存在，求出三角形的最大内角．

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Your Teen Is Falling Asleep in Class

    Teens have a busy morning schedule as they need to wake up and get moving very early in order to catch a bus and get to school by the required time. This means teens need to get their rest the night before or they will be too tired to learn anything at school. ____

    When a teen falls asleep in class, two things happen: he/she misses what is being taught and he/she loses the respect of the teacher. He/She may also receive a consequence from the school, depending on the classroom discipline policy. ____

    To prevent your teen from being sleepy in class, try these three tips：

    *Set a time for “lights out” on school nights. This is never any later than 10 p.m. and preferably 9 p.m. ____ Soft music can be on and used to help calm your teen.

    *Help your teen develop a nighttime routine that involves activities that slow them down for the end of the day. ____ Turning off the computer and disconnecting from friends and the excitement of the day an hour before bedtime will also help your teen relax.

    * ____ This will reinforce (增强) what it feels like to be rested and capable of accomplishing what he/she wants.

A．What's worse, they may even fall asleep in class.

B．Set a good example and show him/her your love for learning.

C．Taking a bath and reading are two activities that work well.

D．Point out the positives after your teen has had a good night's rest.

E．All of these things affect your teen's academic success and can be avoided.

F．“Lights out” means the computer, television, lights and cell phone should be off.

G．While your teen keeps his/her goals in line with your expectations, he/she may have his/her own goals.

    Many animals recognize their food because they see it. So do humans. When you see an apple or a piece of chocolate you know that these are things you can eat. You can also use other senses when you choose your food. You may like it because if smells good or because it tastes good. You may dislike sonic types of food because they do not look, smell or taste very nice. Different animals use different senses to find and choose their food. A few animals depend on only one or their senses, while most animals use more than one sense.

    Although there are many different types of food, some animals spend their lives eating only one type. The giant panda eats only one particular type of bamboo. Other animals eat only one type of food even when given the choice. A kind of white butterfly will stay on the leaves of a cabbage, even though there are plenty of other vegetables in the garden. However, most animals have a more varied diet. The bear eats fruits and fish. The fox eats small animals, birds and fruits. The diet of these animals will be different depending on the season.

Humans have a very varied（广泛的）diet. We often eat food because we like it and not because it is good for us. In countries such as France and Britain, people eat foods with too much sugar. This makes them overweight, which is bad for their health. Eating too much red meat and animal products, such as butter, can also be bad for the health. Choosing the right food, therefore, has become an area of study in modern life.