Q: You can buy a CO detector at any home improvement store or major retailer. They vary greatly in price but cost as little as $15. There are a number of features you should consider when making your purchase.  A CO detector should be able to emit at least an 85-decibel sound that can be heard within 10 feet. If you or someone in your house has hearing problems, you may want one that has a louder horn.  Some detectors come in sets and can be connected with each other. When one goes off, the others will as well. This is ideal for a larger domicile.  Check the lifespan of the sensor as they can wear away. Your unit’s sensor filament should last at least five years.  Some detectors offer a digital display that will give you an exact readout of the CO measured in the air. This feature is not necessary but may help you detect harmful accumulations more quickly. For a small apartment, you can use only a single detector but if you have more than 3 rooms, you’ll want multiple detectors. You’ll want to place them strategically in areas where CO accumulates.  CO is lighter than air so it will rise toward the ceiling. Place the detectors on the wall as close to the ceiling as possible.  If your home has multiple stories, you should have at least one on each level. Place one detector near each sleeping area.  Don’t place them in the kitchen, garage, or near a fireplace. These rooms will experience short-term spikes in CO that aren’t harmful and will set the alarms off unnecessarily. The display and sound settings vary greater from brand to brand and model to model so you will need read the manual thoroughly. Most digital displays will provide a number that tells you the amount of CO in Parts-per Million (PPM) and some include a timer to specify the length of the testing time. Many will include a volume adjuster, a backlighting option, and auto power-off feature. The unit should come with instructions to install. Make sure you have the necessary tools while you are out shopping for the detector so you don’t need to make multiple trips.  Make sure you have a sturdy ladder to place them up high on the wall. You’ll probably also need a power drill. The screws will likely come with the unit. Some units are hardwired or plugged in but most run on batteries. The unit should emit a noise when the batteries are low. Make sure you also have at least one spare pack of the necessary battery type at all times.
A: Purchase detectors. Consider optional features. Find the right spots. Understand the display and sound settings. Install the detectors. Replace the batteries.

Article: Most laptop cases are made of hard plastic. You should remove the cover when painting to avoid painting the laptop itself. Use painter’s or masking tape to protect any parts of the cover that you don’t want to paint. Lay down newspaper on a hard surface. Use this surface for all your work. Make sure that the surface is completely covered to protect it from the paint.  If you do not have any old newspaper lying around, any kind of paper or an old tablecloth will work. Make sure the area is well ventilated and consider using a mask to prevent inhaling any fumes while spray painting. Inhaling fumes from spray paint can be dangerous.  Avoid areas with any open flame or extreme heat. Spray paint is flammable! This will give you a better surface for painting. It will also reduce the likelihood of the paint flaking off. Don’t sand too hard. Your goal is to create a slightly rough surface that will better hold paint, but not scratch the surface up completely.  Use 100-180 grit sandpaper to prepare plastic for paint.   Optionally, coat the case in primer. Primer can help prepare the surface for painting, but is not always necessarily with plastics. Spray paints for plastics are available in a variety of colors at most craft stores. Use the area you have set up previously. Again, be sure that it is well ventilated and away from any open flame.  Spray evenly and avoid building up too much paint in any one area. This will help your paint job from appearing blotchy and uneven. Apply two to three coats, letting the cover dry in between coats. Using several coats will help ensure complete coverage.
Question: What is a summary of what this article is about?
Remove the cover from the laptop. Prepare your painting area. Lightly sand the part of the laptop cover you want to paint. Paint your laptop cover using spray paint.

Problem: Article: There will be several tabs along the top of the Sounds pop-up, including: "Playback," "Recording," "Sounds," and "Communications." You may have only one microphone showing, or you may have several. If the microphone you want to use is not showing up in the list, try one of the following:  Make sure that the microphone you want to use is plugged in, and that it's in the correct jack socket. The color of the socket may vary; it should have an icon of a microphone right next to it. If you are on a laptop, you will likely have a microphone already built into your computer; however, you can still plug in a higher-quality one. Right-click one of the microphones from the list, and make sure that the "Show disabled devices" is checked. This should bring up all of the microphones available.  This will now be your active microphone.  You can also select "Set as default communication device." This means that you'll only be able to use the microphone to chat with other people in programs, such as Skype and video games. If you want to make recordings on your computer, then select "Set as default device."
Summary: Make sure that the "Recording" tab is open. Find the microphone that you want to use. Right-click on the microphone you want to use and click on it. Select "Set as default device" to change the microphone.

Q: The key aspect of a good unit test is that it checks just one portion of a program. Whether you are looking to test an existing program, or planning tests for a program that isn’t written yet, you’ll need to break it down into discrete parts (“units”). You’ll then write a unit test for each one. The definition of a “unit” varies widely depending on the type of program you are developing. A unit could be a class, but also a single function or procedure. A unit test can be used to check two kinds of scenarios. State-based testing is used to see if a program unit produces proper or expected results. Interaction-based testing, on the other hand, is used to see if a unit sets anticipated methods into action. To write a good test, you’ll need to identify what you are trying to test for, so keep one of these approaches in mind as a model. Keep in mind that you’ll need to write lots and lots of unit tests. You’ll want to run a unit test for every portion of your program. Keeping your tests simple will have several benefits:  Simple tests will help ensure that you really are testing only one unit at a time. The tests’ code will be reliable. If you have complex test code, it will be more prone to problems, making it just that harder to see bugs in the code of the program you are testing. The tests will be faster, decreasing the overall amount of time it takes to do the testing. A simple test will be readable, meaning you may see some potential problems just by looking at the code itself. Seasoned developers know that there are different ways to test a program. Unit tests are narrow, specific, and look at only one portion of a program. Integration tests, on the other hand, look at the whole program in a real environment. In other words, unit testing ensures that the individual parts of a program work, while integration testing verifies that the parts work together. Integration tests also usually require external elements, such as web servers or a database. To keep unit tests controlled, write them so that they don’t require external elements.
A:
Map your program into units. Determine if you need state-based or interaction-based testing. Plan simple and readable tests. Differentiate unit tests from integration tests.