feat: examples

ex/theme-02-to-be/practice-03.md

@@ -2,6 +2,8 @@
 
 ### Exercise 7. Write am / is / are
 
+Example: I ___ Alex. -> I am Alex.
+
 1. The robot ___ blue.
 2. I ___ ready.
 3. They ___ at the park.
@@ -9,6 +11,8 @@
 
 ### Exercise 8. Choose the correct word
 
+Example: apple / banana -> apple
+
 1. He (is / are) a pilot.
 2. We (am / are) busy.
 3. It (is / am) red.
@@ -16,6 +20,8 @@
 
 ### Exercise 9. Match
 
+Example: 1 -> b
+
 1. I am
 2. She is
 3. They are