Do you like to watch the advertisements on TV if _________?
11. It is because people are likely to stay indoors ______ the virus can spread easily ______ people often catch colds.
12. He gave us a nod and muttered a “yes” after _______ seemed like hours.
13. In any case, parents should make clear _______, if any thing, the children are expected to pay for with the money.
14. Many new games are designed on the computers all the time; people of all ages ______ these games.
15. --- Who are the teenagers gathering at the school gate? --- Well, if you _____ know, they are all my visiting students.