Sentence check

are these correct?

1. Some adults exhibited homosexual tendency when they were at a young age.
2. My family frowns on cohabitations without a marriage.
3. Too much parental controls inhibit children's creative minds.
4. Passengers are prohibited from leaving their seats until the plane has come to a complete stop and the fasten-seat-belt sign has been turned off.

Not bad at all!

Let's do the real mistakes first:

In sentence 3, you have "much ... controls". You need "many ... controls". "much" goes with a singular noun; "many" with a plural.

In sentence 1, "homosexual tendencies" is what you need to write. A singular noun ("tendency") can't occur without a determiner ("a", "the", etc.).

The others are just minor details:

In 1. it would be more usual to see: "tendencies when they were young" or "tendencies at a young age".

In 2. "marriage" could be used as well as "a marriage". (Either a count or a noncount interpretation of "marriage" is possible.)

Hope that helped.

Ah, yes. I skipped that one, and haogide caught it!
"cohabitation" is a noncount noun. As such, no plurals allowed!

It is noncount because you are talking about "the practice of cohabitation" (in general) or "the state of cohabitation" (in general), not (specific) "instances of cohabitation".

I know that count/noncount problems can be difficult and that sometimes explanations don't help, but this is the best explanation I have at the moment!

okay, two more tries:

1. Rampage loggings have destroyed Bengal tiger's habitats in South Asia.
2. The first inhabitants of Taiwan, known as the Natives who comprise less than 2% of the Island's population, are believed to have migrated from islands south of Taiwan thousands of years earlier than the Chinese settlers.

thanks. I don't know what to do with the non-count noun, singular and plural, etc. where do I start? I think my problems are article and non-count nouns.