At the end of the class, the teacher _______ the main points of the lesson in three sentences.
| A．summed up | B．picked up | C．brought up | D．took up |
11. It is because people are likely to stay indoors ______ the virus can spread easily ______ people often catch colds.
| A．and, that | B．so, that | C．therefore, so | D．that, that |
12. He gave us a nod and muttered a “yes” after _______ seemed like hours.
| A．that | B．which | C．it | D．What |
13. In any case, parents should make clear _______, if any thing, the children are expected to pay for with the money.
| A．that | B．which | C．what | D．How |
14. Many new games are designed on the computers all the time; people of all ages ______ these games.
| A．are playing | B．had played | C．have been playing | D．Play |
15. --- Who are the teenagers gathering at the school gate?
--- Well, if you _____ know, they are all my visiting students.
| A．need | B．must | C．may | D．Will |