1. Shall we go to a movie?

1-2. Shall we go to the movie?
2. Shall we go to see a movie?
3. Shall we go to see the movie?
4. Shall we go to the movies?
5. Shall we go to the movie?

(Are all the sentences grammatical? I think #4 is correct. What about # 5?)

6. The bag was gone.
6-2. The bag disappeared.
(Are both the same?)

7. He was gone.
7-2. He disappeared.
(Are both the same?)

8. There are two McDonald's here.
8-2. There are two McDonals's' here.
8-3. There are two McDonald'ses here.

(Which one is correct?)

All of the first five are all correct. When you say "a movie," you mean any movie. "The movie" implies a specific movie that you've already talked about. The exception is # 4 -- "the movies" -- which means any movie.

# 6 and 7. They are almost the same. With 6-2, you're implying that you don't know what happened to the bag. With 6-1, it's not clear whether you know what happened to the bag. For instance, you might say, "I saw a group of men around the bag -- and then it was gone."

Only the first # 8 is correct. The other two are not correct.

1. Shall we go to a movie?

1-2. Shall we go to the movie?
2. Shall we go to see a movie?
3. Shall we go to see the movie?
4. Shall we go to the movies?
5. Shall we go to the movie?

All of these sentences are grammatically correct, although they have slight differences in meaning.

1. "Shall we go to a movie?" - This is a general question asking if the person wants to go to any movie or a movie in general.
1-2. "Shall we go to the movie?" - This is more specific, implying that there is a specific movie in mind or perhaps referring to a movie that has been previously mentioned.
2. "Shall we go to see a movie?" - This sentence is asking if the person wants to go and see a movie.
3. "Shall we go to see the movie?" - This sentence suggests that there is a specific movie in mind that the person wants to see.
4. "Shall we go to the movies?" - This is a more casual way of asking if the person wants to go to the movie theater to watch a movie.
5. "Shall we go to the movie?" - This sentence is grammatically correct, but it sounds a bit odd and less common compared to the others. It might be better to say "Shall we go see a movie?" or "Shall we go to the movies?"

6. The bag was gone.
6-2. The bag disappeared.

Both sentences convey the same meaning, but there is a slight difference in emphasis. "The bag was gone" simply states that the bag was no longer there. "The bag disappeared" implies that the bag disappeared mysteriously or unexpectedly. So, while they are similar, "disappeared" suggests a more sudden or unexplained disappearance.

7. He was gone.
7-2. He disappeared.

Similar to the previous pair, both sentences convey the same meaning, but with a difference in emphasis. "He was gone" indicates that he was no longer present. "He disappeared" implies a sudden or unexpected disappearance. So, both sentences are grammatically correct, but "disappeared" suggests a more mysterious or unexpected disappearance.

8. There are two McDonald's here.
8-2. There are two McDonals's' here.
8-3. There are two McDonald'ses here.

The correct sentence is "There are two McDonald's here." The possessive form "McDonald's" is used as it indicates there are two locations of the McDonald's restaurant. Adding an "s" after the apostrophe is incorrect in this context. So, option 8-2 and 8-3 are grammatically incorrect.