Questions 18 to 21 refer to the following text. HOW TO USE A TOASTER 1. Insert a slice of bread into each toaster slot. 2. Choose the toasting level, usually it is from the lightest to the darkest. This will allow you to choose how dark the toast to be. 3. Wait until the toasting process finished, usually the process only take a minute. 4. Pick the bread when the toasting process is finished and the bread pops up from the toaster slot. 5. The toasted bread is ready. Then, you can put it on a plate and put some butter on it. 6. And last, don’t forget to unplug the toaster cable to evade the chance of electrical shock. What is the text mainly discussed?

Questions 18 to 21 refer to the following text.

                                           HOW TO USE A TOASTER
1.    Insert a slice of bread into each toaster slot.
2.    Choose the toasting level, usually it is from the lightest to the darkest.
This will allow you to choose how dark the toast to be.
3.    Wait until the toasting process finished, usually the process only take a minute.
4.    Pick the bread when the toasting process is finished and the bread pops up from the toaster slot.
5.    The toasted bread is ready. Then, you can put it on a plate and put some butter on it.
6.    And last, don’t forget to unplug the toaster cable to evade the chance of electrical shock.

What is the text mainly discussed?