Jack almost fell off the cliff, but managed to _____ until help came.
| A．keep on | B．catch on | C．count on | D．hang on |
The classroom ______ 30 feet long.
| A．measures | B．is measured | C．has | D．has length |
As middle school students, we _____ the police to keep order.
| A．are used to help | B．used to helping |
| C．used to help | D．used to be helped |
The teacher said he needed _____ boys besides his students _____ the classroom.
| A．20 other; clean | B．20 more; to clean |
| C．20 more; cleaning | D．another 20; clean |
If you keep on, you’ll succeed _______.
| A．in time | B．at one time |
| C．at the same time | D．on time |
We had a hard life _____ in my childhood.
| A．at a time | B．at all times |
| C．at one time | D．at any time |