填空题. A. alert B. awareness C. burning D. check E. come across F. conscious G. curb H. direction I. likely J. location K. notify L. run into M. sustaining N. watch out O. wary If you own an iPhone, there's a very good chance you 21 battery problems now and again—times when you wish you had the battery life to take one more photo, look up the 22 of a restaurant or make a quick phone call. But the more we use and rely on our smartphones, the more 23 they are to run out of juice when we need them most. However, with a bit of 24 of how you use your iPhone—and what apps you're using on it—you can 25 your iPhone's battery hogging tendency (电池蓄电能力). We'll take a look at what types of apps commonly drain your battery power and look into the ways you can keep your iPhone juiced up. The biggest battery drain by far will be the apps that you're always using. Do you keep Facebook open on your iPhone and 26 it regularly? Do you have AOL Instant Messenger (AIM) open on your phone to talk to friends on the go? Or Pandora streaming music in the background? Some of these apps will even keep running in the background, 27 battery life even when you aren't paying any attention to them. Looking at our examples, Facebook will actively 28 you of new updates or messages, AIM is constantly checking to see if your friends are on or offline and streaming apps like Netflix, Hulu, Pandora or Spotify will keep streaming until you tell them to stop. And as long as these apps are active and doing things, they're burning through your battery life. In addition to your favorite apps, you need to be 29 of apps that keep your screen active (though you might not think about it, it takes a lot of energy to keep your phone's screen light up) or put a strain on your smartphone's internal (内部的) processor. Beyond the video streaming apps we've already mentioned, be on the 30 for games: they might be fun, but they'll cut sharply into your battery life! Video and photo editing apps like iMovie and iPhoto also take a lot of power to run, so keep them closed unless you need them.