Hacker review of clear sentence

E-ex8-1 Active vs. passive verbs
I learned what is different between active and passive verbs. it is little useful.
E-ex 8-2 active vs. be verb
Be verb is the same with passive verbs, so E-ex 8-2 is the same with E-ex8-1.
E-ex 8-3 Active verbs
It help us to know how to make good grammar use active verbs.
E-ex 9-1, 2, 3 Parallelism
This part is ready to help me to make nice sentences.
E-ex 10-1 10-2Needed words
I knew that how to use some meaning less and useful words to make good sentences.
E-ex 11-1, 11-2, Mixec construction
those exercises are not very help me to make sentences.
E-ex 12-1 and 12-2 Misplaced modifiers 
Those parts are difficult for me..
E-ex 12-3 and 12-4  Dangling modifiers
Those parts  help me a lot,  I will do more exercises to improve my skill.
E-ex 13-1 13-2, 13-3 and 13-4 Shifts
shifts are including tense, person and number. it is good for me to study more.
E-ex 14-1 and 14-2 Choppy sentences
It is easy for me, but I will still study it.
E-ex 14-3 Subordination
It helps me a little.