若$\frac{\sqrt{1-x}}{x+3}$在实数范围内有意义，则x（    ）

下列句子中标点符号使用正确的一句是（    ）

      Microblog(微博) is used by more and more people in China. Do you know what it is? Microblog makes the people around the world to know each other better. It helps people to find the information that they need easier, also to get some information about the world they did not know before.
       Many famous people are using microblog now, including singers, TV hosts and artists. Yao Chen once became the queen of microblog because her microblog has over 1.3million followers; Li Yuchun sent a microblog and got 11760 comments(评论) within 24 hours; Cai Kangyong, who is a famous TV host and famous writer in Taiwan, has 15143 more followers within 24 hours.
     Why is microblog so popular? The most important reason is that it is convenient(方便的). People need not use too much time to write the articles to express their feeling. They can write at most 140 words, and then send it through computers or mobile phones onto the microblog. They can use it anytime, anywhere.
       Many of my friends use microblog to share what they see, hear and think in a sentence or a photo with others. Also, they can follow their friends' or their favorite stars' microblogs. Microblog is very hot now!
Have you microblog today ?
根据短文内容，完成下列句子。