---I’m sorry, but there is no smoking on this flight.
---Oh, I _____that. Sorry, I won’t again.
| A．don’t know | B．didn’t know | C．won’t know | D．haven’t known |
With ________ word “PM 2.5” repeatedly appearing in ________ media reports, the public can’t help wondering what it really means.
| A．the; \ | B．a; the |
| C．the; the | D．\; the |
We have just heard a warning on the radio _____________ a typhoon may be on its way．
| A．what | B．when | C．which | D．that |
I will spend half of my holiday practicing English and _____________ half learning drawing．
| A．another | B．the other |
| C．others | D．other |
I ______________ have passed my examination easily，but I made too many stupid mistakes．
| A．must | B．will | C．shall | D．could |
Mom，don’t you think it's OK to play once in a while ____________ it doesn’t affect my studies?
| A．even if | B．unless |
| C．so that | D．as long as |