1. Tom is one year older than John,

2. Tom is twice older than John.
3. Tom is twice as old as John.
4. Tom is a little older than John.
5. Tom is two years older than John.
6. Tom is older than John by two years.
7. Tom is much older than John.
8. Tom is _________________.
....................................
Are they all grammatical? Do you have some more expressions suitable for the blank?

All except 2 look fine.

An alternate for 1 is this: Tom is a year older than John.

An alternate for 5 is this: Tom is a couple of years older than John.

Let's analyze the given statements to determine if they are grammatically correct and explore additional expressions for the blank:

1. "Tom is one year older than John."
- This sentence is grammatically correct. It implies that there is a one-year age difference between Tom and John.

2. "Tom is twice older than John."
- This sentence is not grammatically correct. The correct phrasing would be "Tom is twice as old as John." In this case, we use "twice as" to compare the ages of Tom and John.

3. "Tom is twice as old as John."
- This sentence is grammatically correct. It conveys that Tom's age is twice that of John.

4. "Tom is a little older than John."
- This sentence is grammatically correct. It suggests that Tom has a slightly higher age than John.

5. "Tom is two years older than John."
- This sentence is grammatically correct. It states that there is a two-year age difference between Tom and John.

6. "Tom is older than John by two years."
- This sentence is grammatically correct. It indicates that Tom's age exceeds John's age by a period of two years.

7. "Tom is much older than John."
- This sentence is grammatically correct. It implies a significant age difference between Tom and John, with Tom being considerably older.

To explore more expressions suitable for the blank, we can consider the following options:
- Tom is significantly older than John.
- Tom is considerably older than John.
- Tom is notably older than John.
- Tom is substantially older than John.
- Tom is markedly older than John.
- Tom is vastly older than John.
- Tom is significantly senior to John.
- Tom is notably more aged than John.
- Tom is considerably further along in age than John.

The choice of expression will depend on the desired level of emphasis on the age difference between Tom and John.