present continuous

All of tenses actually are based on simple present. so if you are able to make the sentence with that tense you will feel easy to make a sentence in another tense. and now we are going to study present continuous.
well, if you know the word Do or Does simple present you must know and memorize the keyword in present continuous. they are is, am , and are. and after that followed with present particilpe or V ing.   is for He, She, and It, am for I, and are for They, we, and You. for more explanation see the example below.

remember that sentence must have subject and verb at least.

               S                          V                             0
+            She                 climbs                   the wall   (in simple present)
+            she     is         climbing              the wall
-             she  is not    climbing              the wall
?  is       she                 climbing              the wall?

I think that is clear. and if you want to exercise your self click the link below:
for exercise 1 click here
for exercise 3 click here
for exercise 4 click here
for exercise 5 click here
for exercise 6 click here
for exercise 7 click here
for exercise 8 click here
for exercise 2 click here
for answer key 1 click here
for answer key 2 click here