In English, there are several modal auxiliary verbs that are used to express different degrees of possibility, probability, and certainty. Here’s a breakdown of how these modals are used:
1. Possibility:
- May / May Not: Used to indicate a possibility or likelihood.
- “Your laptop may be in the living room.” (There’s a possibility it’s there.)
- “I may come to your party but I am not sure.” (Possibility of attending.)
- “He may not like chicken but he may prefer fish.” (Possibility of preference.)
- Might / Might Not: Similar to “may,” used for expressing a less certain possibility.
- “He might come to the school to talk about his son.” (Less certain possibility.)
- “I might be in the scout group next summer but I’m not sure.” (Less certain possibility.)
- “There may be a bank somewhere here.” (Expressing the possibility of a bank’s presence.)
2. Certainty:
- Must / Mustn’t: Used to indicate a high degree of certainty or necessity.
- “There has been nobody here. Everybody must be in the match.” (High degree of certainty.)
- “They must be very happy because they passed the university entrance exam.” (Expressing a strong belief.)
- “This car costs a lot of money. It must be one of the most expensive cars in the world.” (Expressing strong belief in the cost.)
- “He can’t win the match because he doesn’t train a lot.” (Strong certainty that he won’t win.)
- “I am sure Janet must be in the mall.” (Expressing high certainty about Janet’s location.)
In summary, “may” and “might” are used to express possibilities, with “may” indicating a slightly higher degree of certainty than “might.” On the other hand, “must” and “mustn’t” are used to express a high degree of certainty or necessity, with “must” indicating a strong belief or certainty, and “mustn’t” indicating a strong prohibition or necessity.