The math problem is _____ difficult that only _____ students can work it out.
| A．too; a few | B．so; a few | C．so; a little | D．enough; little |
________ fathers are both doctors.
| A．Jim's and Bob's | B．Jim's and Bob |
| C．Jim and Bob's | D．Jim and Bob |
Please __________ the light when you leave the classroom.
| A．turn on | B．turn up | C．turn off | D．turn down |
When you go _________ the street, you must be careful.
| A．crossing | B．cross | C．across | D．pass |
I ______ an hour finishing my homework yesterday.
| A．cost | B．paid | C．spent | D．took |