topic sentence.( I need your opinions)

[bosunyum]

what do you think of the following topic sentences.If you think it is not a good topic sentnece, please give your opinions.

1.A parent is not always the best teacher for children.

2. I sometime rely upon my parents.

3. The biggest present of one's life is a good friend.

4. Friends are the most important part of your life.

5.Juealousy is bad for your health.

6. There are many songs about jealousy.

[Tdol]

A lot depends on what comes in the rest of the paragraph. However, I don't think much of the second as it is a bit vague- 'sometimes' is almost an emtpy word to me and doesn't really convey much, so it doesn't make it clear the degree of the depency and whether this is good or bad, or both. 3 doesn't really work because 'present' doesn't fit the context- how about something like 'the greatest addition to one's life is a good friend'?