There some students on the playground．（ ）
| A． |
is |
B． |
have |
C． |
has |
D． |
are |
—______ do you go to the school library？
—Twice a week.
A．How longB．How oftenC．How soonD．How much
Mary shut the window just now ______ she could keep the insects out.
A．so thatB．whenC．tillD．after
This year's Beijing Music Awards will be covered ______ on Sunshine TV this Saturday.
A．livelyB．aliveC．livingD．live
—Mum，where is David？
—He ______ to see the science fiction film Back to the future.
A．is goingB．goesC．has goneD．was going
The Communist Party of China will have its 100th birthday ______ July 1，2021.
A．inB．onC．forD．at