answering explore objects

Author: TzeMingHo

Sprint-1/4-stretch-explore/objects.md

@@ -5,12 +5,22 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
+I got ƒ log() { [native code] }
+Chrome is telling me console.log a built-in function.
 
 Now enter just `console` in the Console, what output do you get back?
+The output is the console object, which has many built-in methods, such as assert, clear, and context.
 
 Try also entering `typeof console`
+The type of console is an object.
 
 Answer the following questions:
 
 What does `console` store?
+A console contains its properties, and many of its properties are built-in methods that we can call.
+
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+The syntax console.log references to the log method built-in the console object, whereas console.assert references to the assert method.
+The log method can output message to the console.
+The assert method can output a error message when an assertion is false.
+In particular, the "." is a accessing method syntax. As a console is an object which has many built-in methods, the "." can refer to the corresponding method after the ".", such as log and assert.