Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Facebook is a for-profit online social media and social networking service. The Facebook website was launched on February 4th, 2004 by Mark Zuckerberg, along with fellow Harvard College students and roommates. Since 2006, anyone age 13 and older has been allowed to become a registered user of Facebook though variations exist in minimum age requirement, depending on applicable local laws.

Over 25 million people in the Uk use Facebook. That’s 45% of population! And on average, each user spends over six hours a month on Facebook. Though not the highest this is a considerable number. Is Facebook is a dangerous obsession or just harmless fun? Seventeen-year-old Bethan has written on her blog about what it was like to stop using Facebook. I think I am a Facebook addict. I log on to Facebook everyday to chat to my friends real friends and loads of online friends. Sometimes I have ten conversations going at the same time. I upload photos and update my Facebook profile all the time. But recently I’ve started to feel worried if I am offline for more than a few hours. And then last week I forgot to meet a real friend because I was online! I’ve realised I could have a problem. So I’ve decided to give it up for a while.
I found it really hard. Facebook and my friends demanded to know why I had left. I spent the first few evenings wondering what everyone was chatting on Facebook. I even phoned a couple of friends to find out. The fourth night I wasn’t quite so bad. I actually concentrated on my homework better and I had more time to watch my TV programmes. And I spoke to my friends during the day at school. At the end of the first week, I reactivated my account, I think Facebook is fun and it’s useful for posting messages to friends and sharing photos. But I’ll try not to spend so much time on it in the future.

The highlight word “it” in the passage refers to _________.

The flights ________ last year because of the thick fog. were being cancelled