Update article.md

Grammar suggestions

1-js/09-classes/06-instanceof/article.md

@@ -2,7 +2,7 @@
 
 The `instanceof` operator allows to check whether an object belongs to a certain class. It also takes inheritance into account.
 
-Such a check may be necessary in many cases, here we'll use it for building a *polymorphic* function, the one that treats arguments differently depending on their type.
+Such a check may be necessary in many cases. Here we'll use it for building a *polymorphic* function, the one that treats arguments differently depending on their type.
 
 ## The instanceof operator [#ref-instanceof]
 
@@ -46,7 +46,7 @@ alert( arr instanceof Object ); // true
 
 Please note that `arr` also belongs to the `Object` class. That's because `Array` prototypically inherits from `Object`.
 
-Normally, `instanceof` operator examines the prototype chain for the check. We can also set a custom logic in the static method `Symbol.hasInstance`.
+Normally, `instanceof` examines the prototype chain for the check. We can also set a custom logic in the static method `Symbol.hasInstance`.
 
 The algorithm of `obj instanceof Class` works roughly as follows:
 
@@ -68,7 +68,7 @@ The algorithm of `obj instanceof Class` works roughly as follows:
     alert(obj instanceof Animal); // true: Animal[Symbol.hasInstance](obj) is called
     ```
 
-2. Most classes do not have `Symbol.hasInstance`. In that case, the standard logic is used: `obj instanceOf Class` checks whether `Class.prototype` equals to one of prototypes in the `obj` prototype chain.
+2. Most classes do not have `Symbol.hasInstance`. In that case, the standard logic is used: `obj instanceOf Class` checks whether `Class.prototype` equals to any prototype in the `obj` prototype chain.
 
     In other words, compare one after another:
     ```js
@@ -107,7 +107,7 @@ By the way, there's also a method [objA.isPrototypeOf(objB)](mdn:js/object/isPro
 
 It's funny, but the `Class` constructor itself does not participate in the check! Only the chain of prototypes and `Class.prototype` matters.
 
-That can lead to interesting consequences when `prototype` property is changed after the object is created.
+That can lead to interesting consequences when a `prototype` property is changed after the object is created.
 
 Like here:
 
@@ -186,7 +186,7 @@ let user = {
 alert( {}.toString.call(user) ); // [object User]
 ```
 
-For most environment-specific objects, there is such a property. Here are few browser specific examples:
+For most environment-specific objects, there is such a property. Here are some browser specific examples:
 
 ```js run
 // toStringTag for the environment-specific object and class: