Any grammar mistake? there are few cameras in parks and there is no way that you could know what happen when you are away.

is this sentence understandable? there are few cameras in parks and there is no way that you could know what happen when you are away.

there is an increasing number of people that have sitting disease？？ anyone can rewrite my sentence? thank you very much. I find it pretty awkward

Is this sentence okay? Another personality I like is industrious

have many entertainment on weekends? how to say it properly? I have many entertainment on weekends?

at or over 18. Is it okay to say so....? Is it okay to say so....? at the age of and over the age of 18?

undertake fees? or tuition? is this make sense? undertake fees? or tuition? is this make sense?

where or that? My place where I live is very quiet. where or that here, in this sentence?

is this business invitation clear? For the business collaboration purpose, company A invites The President Mr. X of the subsidiary B Co.,Ltd. of C ，The Vice-president Mrs.of subsidiary D Co.,Ltd. of C to visit UKfor business trip.