1. It's half past five.
2. It's half to six.
[Can we use both expressions? Which one is commonly used?]
3. It is nine forty-five.
4. It is nine forty five.
5. It is nine-forty-five.
6. It is nine-forty five.
[Which expressions are grammatical?]
In speech, 1, 3, 4, 5, and 6 are correct.
In writing, 1 and 3 are correct.
1. The expression "half past five" means it is 30 minutes past 5 o'clock. This is commonly used and easily understood.
2. The expression "half to six" is less common and not as widely used. It means it is 30 minutes before 6 o'clock. While it may still be understood in context, "half past five" is the more commonly used expression.
Regarding the third set of expressions:
3. "It is nine forty-five." This is a grammatically correct way to express the time.
4. "It is nine forty five." This is also grammatically correct as it follows the basic structure of indicating the hour, then the minutes.
5. "It is nine-forty-five." This is another correct way to express the time using hyphens to connect the numbers.
6. "It is nine-forty five." This expression is not grammatically correct because it does not use any punctuation or hyphens to separate the numbers.
Overall, expressions 3, 4, and 5 are all considered grammatically correct and acceptable ways to write or say the time "nine forty-five."