Li Lei's parents ______ doctors.
| A．are all | B．are both | C．all are | D．both are |
The little boy is only six years old, _________ he can make wonderful model cars.
| A．so | B．or | C．but | D．/ |
Please knock at the door ________ you come into the room.
| A．before | B．after | C．until | D．while |
A tourist will easily lose his way in Beijing ______ he has a map or a guide.
| A．if | B．because |
| C．unless | D．when |
Be quick, ＿＿＿we’ll be late for school.
| A．and | B．or | C．so | D．/ |
--- I won’t go to the party tonight.
--- ______ you told me you would. What’s the matter?
| A．So | B．Or | C．Because | D．But |