This book is worth _____.
In the lecture, little Tom kept silent all the time unless _________ to express his opinion.
_________ are the days when teachers punished students for minor offenses, being late for school, for example.
It is quite impossible that it will rain tomorrow. But if it __________, I would still go to school by bike.
Had she __________ her promise, she would have made it at Beijing University.
Boys in early adolescence are not _________ to the cinema because the film is not suitable for them.