---Don't skate on the lake!
---Why not? Isn't it thick enough___________?
| A．to skate | B．skating on | C．skating | D．to skate on |
John didn’t know ____ the medicine.
A. what to take
B. how to take
C. where to eat
This is the question______ we are talking about now.
A. which B. who C. what
There is _____800-meter-long road behind____ hospital.
A. an, an B. an, theC. a, the
He improved his English a lot listening to the radio.
| A．with | B．by | C．for | D．on |
The students hurried to the classroom the bell rang.
| A．until | B．as soon as | C．if | D．so that |