如下图所示，视野中除了细胞外还有很多异物，转换物镜和移动装片时异物均不动。据此可判断异物存在于     （   ）

    Here are some tips about how to keep healthy.

1) Healthy food is important. If you want to keep healthy, eat lots of fruit and vegetables. Don't eat much meat.

2) Water is important. Drink water every day. Milk is good for you, too. Don't drink sweet drinks.

3) Exercise is important. You can ride your bike or play soccer. Going swimming is a good idea.

4) Clean air is important. If you are free, you can go to the park and enjoy clean air.

5) Your teeth are important. You should brush your teeth twice a day.

6) Sleep is important, too. Go to bed early. Don't stay up late, or you will feel sleepy.