问题：
There ______ many people ______ in the office, but now nobody is allowed to.
A．used to be；smoking
B．used to have；smoking
C．used to be；smoke
D．used to have；smoke
There ______ many people ______ in the office, but now nobody is allowed to.
| A．used to be；smoking | B．used to have；smoking |
| C．used to be；smoke | D．used to have；smoke |
参考答案：