My grandparents wrote letters to keep in touch with others_________ they were young．（ ）
| A． |
when |
B． |
since |
C． |
after |
D． |
before |
Facial recognition（人脸识别）technology is widely used for payment． ________， we needn't enter the passwords any more．（ ）
| A． |
For example |
| B． |
As a result |
| C． |
What's more |
Gina used to live in the countryside with her parents， but now she is used to ________with her classmates at school．（ ）
| A． |
live |
B． |
living |
C． |
lived |
Do you know that we have already made great progress in 5G？
Oh， ________exciting news!（ ）
| A． |
how |
B． |
what an |
C． |
what |
Tom． together with his friends， often________ to the old people's home to cheer the old up．（ ）
| A． |
go |
B． |
going |
C． |
goes |
Look at the sign "No swimming"， it warns us ________ in the lake．（ ）
| A． |
to swim |
| B． |
not to swim |
| C． |
swimming |