Thats correct
For example when u want to add the word
Family ---> families
Baby ------> babies
If it ended with y preceded by a vowel sound then u dont change y to i
Boy ------> boys
Toy -----> toys
Etc.
A independent clause is a part of the sentence that can stand alone and a dependent one can’t it depends on the independent statement so for number one the dependent clause would be that he would be appointed the independent clause would be the manager is certain