address review concerns

src/doc/trpl/closures.md

@@ -1,9 +1,9 @@
 % Closures
 
-Sometimes it is useful to wrap up a function and free variables for better
-clarity and reuse. The _free variables_ that can be used come from the
-enclosing scope and are "closed over" when used in the function. From this, we
-get the name "closures" and Rust provides a really great implementation of
+Sometimes it is useful to wrap up a function and _free variables_ for better
+clarity and reuse. The free variables that can be used come from the
+enclosing scope and are ‘closed over’ when used in the function. From this, we
+get the name ‘closures’ and Rust provides a really great implementation of
 them, as we’ll see.
 
 # Syntax
@@ -46,10 +46,11 @@ assert_eq!(2, plus_one(1));
 ```
 
 But we don’t have to. Why is this? Basically, it was chosen for ergonomic
-reasons.  While specifying the full type for named functions is helpful with
-things like documentation and type inference, types within closures are rarely
-documented since they’re anonymous, and they don’t cause the kinds of
-error-at-a-distance problems that inferring named function types can.
+reasons. While specifying the full type for named functions is helpful with
+things like documentation and type inference, the full type signatures of
+closures are rarely documented since they’re anonymous, and they don’t cause
+the kinds of error-at-a-distance problems that inferring named function types
+can.
 
 The second is that the syntax is similar, but a bit different. I’ve added
 spaces here for easier comparison:
@@ -65,7 +66,7 @@ Small differences, but they’re similar.
 # Closures and their environment
 
 The environment for a closure can include bindings from its enclosing scope in
-addition to parameters and local bindings.  It looks like this:
+addition to parameters and local bindings. It looks like this:
 
 ```rust
 let num = 5;
@@ -454,7 +455,7 @@ autogenerated name.
 The error also points out that the return type is expected to be a reference,
 but what we are trying to return is not. Further, we cannot directly assign a
 `'static` lifetime to an object. So we'll take a different approach and return
-a "trait object" by `Box`ing up the `Fn`. This _almost_ works:
+a ‘trait object’ by `Box`ing up the `Fn`. This _almost_ works:
 
 ```rust,ignore
 fn factory() -> Box<Fn(i32) -> i32> {