Your commentary and analysis is where you make your transition from the evidence in the story to the point you're trying to prove. It's the bridge that carries your ideas back from the text to your reader.
I know. You've probably been told to use this phrase before. It makes sense why you've been told to use it, but you should understand that this phrase is a crutch: a strategy that helps make a job easier for someone who isn't fully ready to do the job on their own yet. You're in High School now, so it's time to walk on your own.
There are many different ways to phrase your commentary instead of using "this shows that," but if you need a place to start, here is some advice:
Find a noun to describe the kind of thing or moment we see in that moment of the text. This could be an assertion, a question, an argument, a plea, a piece of advice, or millions of other different ideas that could describe what's going on in that moment.
From our earlier example, when George says, "He can talk if he wants to tell you anything" (Steinbeck 25), I would call that a "response."
Use a possessive proper noun to start your sentence (in other words, use someone's name, and add a possessive apostrophe and an s to give ownership of that action). Like this:
George's response
Pick a verb other than "shows." The problem with "shows" is that it is overused. So "illustrates," "demonstrates," "proves," "suggests," or "implies" may work better. There are plenty of other verbs to use in addition to these ones.
The first sentence following a quotation should explain how the evidence in the quotation proves the main idea of your argument to be true. For example, we might come up with something like:
George's response suggests that he is being careful and measured with his language, rather than lashing out in response, which stops things with Curley from getting out of hand.
This way we've used some language ("careful" and "measured") that call to mind our central topic: patience. We've then continued to explain how the George's patience helps to protect people in need (in this case, Curley), by making sure that Curley doesn't do anything violent or aggressive.
The second half of your commentary should explain why the ideas in the first half of your commentary (the reasoning) are interesting, or important. In other words, you should answer the question "Why would anybody care?" This is why it's so important to frame your ideas in the context of exploring real life ideas, because we can never get George to change his actions, but we can learn from George and change our own actions or beliefs as a result (in other words: why we should care).
Similar to your topic sentence, this can be accomplished by changing your wording so that you are focusing a little more broadly on real life things, or patterns of human behavior. So instead of following up a sentence about George with another sentence about George, we could follow with a sentence about patience. Like this:
Patience, especially when facing hostility, can allow de-escalation of situations, so that aggression does not result in needless harm (particularly to defenseless people).
This way, we end our analysis of the quotation by giving insight into real life, rather than ending our analysis with insight into a fictional character. Your reader can learn something useful that might impact the way they live their lives, instead of remaining with a fictional character who cannot change.