根据下面资料，回答1-20题
If you're like many people, you may have decided that you want to spend less time 1 at your phone. It's a good idea：an increasing body of 2 suggests that the time we spend on our smartphones is 3 with our sleep, self-esteem, relationships, memory,attention spans, creativity, productivity and problem-solving and decision-making 4 .
5 there is another reason for us to rethink our 6 with our devices. By chronically raising levels of cortisol, the body's main stress hormone, our phones may be 7 our health and shortening our lives.
Until now, most discussions of phones' biochemical effects have focused on dopamine,a brain chemical that helps us 8 habits—and addictions. Like slot machines,smartphones and apps are explicitly designed to 9 dopamine's release, with the 10 of making our devices difficult to put down. This manipulation of our dopamine systems is 11 many experts believe that we are developing behavioral 12 to our phones. But our phones' effects on cortisol are potentially even more 13.
Cortisol is our primary fight-or-flight hormone. Its release triggers 14 changes, such as spikes in blood pressure, heart rate and blood sugar, that help us react to and 15 acute physical threats. These effects can be life-saving if you are actually in physical 16 —like, say,you're being charged by a bull. But our bodies also release cortisol in response to emotional stressors an increased heart rate isn't going to do much good, such as checking your phone to find an angry email from your boss.
The good news is that if we break this anxiety-driven cycle, we can 17 our cortisol levels, which in turn may both 18 our short-term judgment and lower our 19 for long-term stress-related health problems. To make your phone less stressful, start by turning 20 all notifications except for the ones you actually want to receive.
第（9）题选

A trigger

B lower

C maintain

D cease