Mr Ling．I have some difficulty the article．
Remember it three or four times at least．（ ）
A．to understand；reading
B．understanding；reading
C．understanding；to read
D．to understand；to read
Jack's uncle has got the COVID﹣19． Now he is in a hospital．
．（ ）
| A． |
It doesn't matter |
| B． |
That's all right |
| C． |
I'm sorry to hear that |
| D． |
Be careful next time |
Don't get off the bus until it ．（ ）
| A． |
will stop |
B． |
stop |
C． |
stopped |
D． |
stops |
His office is on the top of the tall building． You should take a lift to the floor．（ ）
| A． |
first |
B． |
thirtieth |
C． |
thirty |
D． |
thirteen |
The air pollution is very serious in our city． Something about it now．（ ）
| A． |
can do |
B． |
must do |
| C． |
was done |
D． |
must be done |
The Great Wall is a place of interest． All of us there before．（ ）
| A． |
has been |
B． |
have been |
C． |
has gone |
D． |
have gone |