As a student, you must ________ your teachers.
Not until yesterday ______ anything about the project that will be completed soon.
There me two maps on the wall: one is a map of China, and ______ is a map of the world.
The conference ______ in Beijing next week is bound to be a great success.
This problem is ______ his ability and 1 don't think he can solve it.
I was almost asleep last night when I suddenly heard someone ______ at the door.