forming noun

I didn't find the rule to form a noun, which noun is suitable for + hood, +ism, +ship, +dom? The world of noun is the big sky, isn't it?

<http://www.flo-joe.co.uk/cae/students/strategy/wform/nouns1.htm>
My score is 2/4. Here are 2 wrong sentences.
The film was praised by the critics for its real ........ in showing the horrors of war.
--> hood --> ism (realism)

During his boy....... he was a rather naughty child.
--> ism --> hood (boyhood)

<http://www.flo-joe.co.uk/cae/students/strategy/wform/nouns2.htm>
My core is perfect:4/4
New words are: motherhood, terrorism, good chance of gaining stardom and recognition

Forming nouns, verbs, adjectives

<http://www.flo-joe.co.uk/cae/students/strategy/wform/nounvbad.htm>

My score is 3/8, so sad. I will do more exercises on that area. My wrong answers are bold, and the rights answers are red.

2. (COMEDY)The ...comedy comedian....... went on stage and received a rapturous welcome from the audience.

3. (IMAGINE)Lots of little children go through a phase of having an .....imagined/ imaginable imaginary...... friend, but they usually grow out of it.

4. (INFECT - 2 changes)I'm doing the cleaning today. Can you get me a bottle of ...infection disinfectant....... from the supermarket.

5. (SWEET)He likes to .....ensweet sweten..... his breakfast cereal with honey instead of sugar.

7. FALSEThe manager was sacked after he tried to .....enfalse falsify..... his accounts.