题目

    Have you ever run into a careless cell phone user on the street? Perhaps they were busy talking, texting or checking updates on WeChat without looking at what was going on around them. As the number of this new “species” of human has kept rising, they have been given a new name — phubbers（低头族）.     Recently, a cartoon created by students from China Central Academy of Fine Arts put this group of people under the spotlight. In the short film, phubbers with various social identities(身份) bury themselves in their phones. A doctor plays with his cell phone while的解是非空集合，则的取值范围是      ．