.
—Must I turn off the gas after cooking?
—Of course! You can never be__________careful with that.
| A．enough | B．too | C．so | D．very |
He _____ himself in Shanghai.
| A．lost | B．missed | C．losing | D．missing |
I was about to leave _____ the telephone rang.
| A．then | B．when | C．that | D．and when |
Children under 10 are not permitted _____ the film.
| A．to see | B．seeing | C．saw | D．watched |
All he was thinking about was ____ he would do with the big sum of money his father gave him.
| A．how | B．what | C．that | D．Whether |
23. The harder we work at our lessons, _____.
| A．the better our grades will be | B． our grades will be better |
| C．will our grades be better | D．even better our grades will be |