1. She was listening to the radio, and she was writing a letter.

2. She listened to the radio, and she was writing a letter.
(Are both ok? Which one is the better of the two?)

1-1. While she was listening to the radio, she was writing a letter.

2-1. While she listened to the radio, she was writing a letter.
(Are both ok? Which one is the better of the two?)

3. He was sitting on his chair, with his legs crossed.
4. He was sitting on his chair with his legs crossed.
(Which one is the better of the two? Do we need to put a 'comma' before 'with'?)

1 and 2 are wordy, but basically correct.

1-1 is correct.

2-1 is correct and slightly better than 1-1 -- less wordy.

The wording in 3 and 4 is fine, but no comma is needed.

1. Both sentences are grammatically correct, but they convey slightly different meanings.

In the first sentence, "She was listening to the radio, and she was writing a letter," the actions of listening and writing are happening simultaneously. This implies that she was doing both activities at the same time.

In the second sentence, "She listened to the radio, and she was writing a letter," the listening to the radio happened first, followed by the writing of the letter. This suggests a sequential order of events.

Which one is better depends on the specific context you want to convey. If you want to emphasize simultaneous actions, the first sentence would be more appropriate. If you want to highlight the order of events, the second sentence would work better.

1-1. Both options are grammatically correct, but they have slightly different nuances.

The sentence "While she was listening to the radio, she was writing a letter" emphasizes that both actions were happening at the same time. It suggests a continuous and ongoing situation where she was multitasking.

The sentence "While she listened to the radio, she was writing a letter" implies a sequential order of events. It suggests that she listened to the radio first, and then started writing the letter.

Again, the choice between the two options depends on the specific meaning you want to convey in context.

3. Both sentences are correct, but the use of a comma before "with" in the fourth sentence is a matter of style and preference.

Using a comma before "with" in the sentence "He was sitting on his chair, with his legs crossed" is called an Oxford comma. Its usage is not a strict rule in English grammar but rather a matter of writing style. The Oxford comma is used to clarify the separation of the elements in a list.

In this case, "with his legs crossed" can be seen as an extra detail about how he was sitting. Adding a comma before "with" helps to clearly differentiate it from the main action, which is "sitting on his chair."

However, it's also acceptable to omit the comma and write the sentence as "He was sitting on his chair with his legs crossed." This version is more streamlined and may be preferred in certain contexts or writing styles.

Ultimately, the choice of using a comma or omitting it depends on your writing style or the specific guidelines you're following.