We should keep an open mind about some strange old wives’ tales, they do have some truth in them.
Achieving a high degree of proficiency in English as a foreign language is not a mysterious _____ without scientific basis.
I must go now. _____, if you want that book I'll bring it next time.
A completely new situation is likely to _____ when the school leaving age is raised to 16.
The illness from which Mary is suffering has now been _____ as hepatitis (肝炎).
These continual _____ in temperature make it impossible to decide what to wear.