Which sentence is correct?

"All I am able to comprehend is that my brothers were right."

or

"All that I am able to comprehend is that my brothers were right."

Both are correct. However, the second one is clearer.

1st one, because accdg to the book i've read, "that" is an essential clause we use. so it's like all I am able to comprehend is what? For ex. My bag "that" my mother bought has been stolen by him. My bag is what? we use "that" to introduce the subject or if it is still unknown! :D

To determine which sentence is correct, let's break down the structure of each sentence:

1. "All I am able to comprehend is that my brothers were right."
2. "All that I am able to comprehend is that my brothers were right."

Both sentences are grammatically correct, but they have slightly different structures.

In the first sentence, the pronoun "I" is used directly after the word "All." This structure emphasizes that the speaker, "I," is the one comprehending something.

In the second sentence, the pronoun "that" is used after the word "All." This structure emphasizes that "that my brothers were right" is what the speaker is comprehending.

Both sentences convey a similar meaning, but the emphasis is slightly different.

If you want to emphasize that it is "I" who comprehends, you should use the first sentence: "All I am able to comprehend is that my brothers were right."

If you want to emphasize what is being comprehended, you should use the second sentence: "All that I am able to comprehend is that my brothers were right."

Ultimately, the choice between the two sentences depends on which aspect you want to emphasize in your statement.