1. He felt it hard to solve the problem.

2. He felt that he should get up early.

3. He felt like a philosopher.

4. The fish smelled like a dead body.

(Are they all grammatical and correct?)

5. The stool is cheaper than the rocking chair.

6. The stool is less expensive than the rocking chair.

7. The stool is more inexpensive than the rocking chair.

(Are the three all the same?)

1 through 4 are correct.

5 & 6 are correct. 7 is correct but it is awkward and not used.

1. Yes, the sentence "He felt it hard to solve the problem" is grammatically correct. It means that he found it difficult to solve the problem.

2. Yes, the sentence "He felt that he should get up early" is also grammatically correct. It means that he had the belief or inclination to wake up early.

3. Yes, the sentence "He felt like a philosopher" is grammatically correct. It means that he had a similar feeling or temperament as a philosopher.

4. No, the sentence "The fish smelled like a dead body" is not grammatically correct. It should be "The fish smelled like a dead body." or "The fish smelled as bad as a dead body." Here, "smelled" is the past tense of the verb "smell," and "like" is used to draw a comparison between the odor of the fish and a dead body.

5. Yes, the sentence "The stool is cheaper than the rocking chair" is grammatically correct. It means that the price of the stool is lower than the price of the rocking chair.

6. Yes, the sentence "The stool is less expensive than the rocking chair" is also grammatically correct. It means that the cost of the stool is lower than the cost of the rocking chair.

7. No, the sentence "The stool is more inexpensive than the rocking chair" is not grammatically correct. It should be "The stool is less expensive than the rocking chair." Here, "less expensive" is the correct phrase to describe the relative cost difference between the stool and the rocking chair.