______ to improve our environment?
| A．What do you think we should do |
| B．Do you think what we should do |
| C．What do you think should we do |
| D．Do you think what should we do |
I am wondering ________ you have read “the Harry Potter series” written by JK Rowing.
| A．when | B．whether |
| C．where | D．what |
It is better for you to walk down the stairs instead of ________ the elevator.
| A．taking | B．to take |
| C．take | D．taken |
He told us that he was tired and thirsty because he ________ in the desert for days.
| A．walked | B．has walked |
| C．had walked | D．would walk |
My mother ________ as an architect since she graduated from Tongji University.
| A．worked | B．has worked |
| C．had worked | D．is working |
According to the timetable, the plane ________ for Los Angeles at 5 in the afternoon.
A. would leave B. left
C leaves D. has left