Omitting relative clauses with 'to be'

When the relative clause has the construction

relative pronoun + 'to be' + ~ing verb

or

relative pronoun + 'to be' + past participle

the relative pronoun and the 'to be' verb can be omitted.
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Examples

relative pronoun + 'to be' + past participle
People that were bitten by mosquitoes should be tested for malaria.
She was wearing a dress which was covered in blue flowers.

relative pronoun+ 'to be' + ~ing verb
Anyone who is smoking will be expelled from school.
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Here are the sentences that we did for dictation at 6:00.

Try to decide if the relative pronouns and 'to be' verbs in the relative clause are optional or not. If they are, put parenthesis around the words which can be omitted. Number 1 has been done as an example.
1. I talked to the man (who was) standing in front of the supermarket.
2. I asked the boys that were playing tennis what the time is.
3. Have you seen the movie that tells the story of the Titanic’s maiden journey?
4. The Chinese restaurant that is near my house has great egg drop soup.
5. We chose three of the sandwiches which were on the table.
6. He was talking on the phone when someone knocked on the door.
7. I always mix up words that are spelled “ei” with words that are spelled “ie”.
8. Plants that can stand hot, dry summer grow well in this area of the country.
9. Only two of the boys wanted to work overtime were able to do it.
10. The child who is playing with the cat is my little sister.