1B sounds odd, I believe it is grammatically correct but I rarely see that type of phrasing.
7C) Doesent make sense the verb to tell isnt a good choice, when you use it you usually have something your referring too, if your going to use tell you want to put an object in the sentence. For example
The tv news told THEM that president Obama was re-elected
Im not sure what your trying to express in 10a and 10b, are you trying to say only childs ( as in one child families) are more common?
In english we can say
A recent survey shows that families with one child are more common.
Alot of people also in casual talk can say
A recent survey shows that only child's are more common.
12a) everyone will understand what your saying if you talk to someone but its very weird to put to do exercise considering exercise is already considered doing something take out to do so it becomes
I asked my father if he had time to exercise.
Dont see anything else wrong they seem to make sense from my perspective