It's necessary for you _______the classroom clean，class．（ ）
A．keepB．keepingC．to keep
We're not sure _____________there'll be_____________ or not tomorrow．（ ）
| A． |
if； rains |
B． |
if； rainy |
| C． |
whether； rain |
D． |
whether； raining |
Where is your uncle？ I haven't seen him for a long time．
Oh， he_____________ Sydney．（ ）
| A． |
went to |
B． |
has been to |
| C． |
has gone to |
D． |
goes to |
Mary， do you prefer weekdays or weekends？
Of course weekends． Because I'm _____________on weekdays．（ ）
| A． |
busiest |
B． |
busy |
| C． |
the busiest |
D． |
much busier |
Plenty of people went to America in _____________．
So they did． My grandfather was one of them． He went there in his_____________．（ ）
| A． |
1990s； thirties |
B． |
1990s； thirty |
| C． |
the 1990s； thirtieth |
D． |
the 1990s； thirties |
China is going to use AI to protect the Great Wall．
Great! AI is so helpful that people _____________use it in their daily life now．（ ）
| A． |
must |
B． |
can |
C． |
shall |
D． |
have to |