Use the correct form of the verbs in parentheses

Use the correct form of the verbs in parentheses. 
a. My dog (21. walk)_______ along quietly when Mr Ba’s (22. attack)_______ him.
b. If you (23. listen)_______ to my advice, you (24. not/be)_______ upset now.
c. Why didn’t you listen while I (25. speak)_______ to you?
d. They (26. start)_______ (27. learn)_______ English when they were 10 years old.
e. This place (28. build)_______ a long time ago
f. The teacher told his students (29. not make)_______ such noise in class.
g. I (30. not/ meet)_______ my friends since last Christmas.