4. A christmas tree ... by my mum yesterday. * decorates
is decorated
was decorated
5. It ... to look for presents under the Christmas tree last night. *
was forbidden
is forbidden
forbiddened
6. I ... a Valentine's card to my friend. *
sent
was sent
were sent
7. Eggs ... for Easter two days ago. *
were painted
was painted
is painted
8. We ... Santa Clause last month. *
were seen
was seen
saw
9. 'Guys" ... on fire when I saw that girl. *
were burnt
burnt
is burnt
10. Guy Fawkes ... as Guido Fawkes. *
known
knew
was known

4. A Christmas tree was decorated by my mum yesterday.
Explanation: In this sentence, we are talking about an action that was done in the past. The verb "decorate" needs to be in the past tense to match the time frame, so we use "was decorated." The subject of the sentence is "A Christmas tree" and it is receiving the action of being decorated by someone, which is "my mum."

5. It was forbidden to look for presents under the Christmas tree last night.
Explanation: In this sentence, we are talking about a rule or prohibition in the past. The verb "forbid" needs to be in the past tense to match the time frame, so we use "was forbidden." The subject of the sentence is "It" and it is the one being prohibited from doing something, which is "to look for presents under the Christmas tree."

6. I sent a Valentine's card to my friend.
Explanation: In this sentence, we are talking about an action that was done by the speaker. The verb "send" needs to be in the past tense to match the time frame, so we use "sent." The subject of the sentence is "I" and it is the one performing the action of sending a Valentine's card.

7. Eggs were painted for Easter two days ago.
Explanation: In this sentence, we are talking about an action that was done to the eggs. The verb "paint" needs to be in the past tense to match the time frame, so we use "were painted." The subject of the sentence is "Eggs" and they are receiving the action of being painted.

8. We saw Santa Claus last month.
Explanation: In this sentence, we are talking about an action that was done by the speaker and others. The verb "see" needs to be in the past tense to match the time frame, so we use "saw." The subject of the sentence is "We" and it is the one performing the action of seeing Santa Claus.

9. 'Guys' were burnt on fire when I saw that girl.
Explanation: In this sentence, we are talking about an action that happened to the noun "Guys." The verb "burn" needs to be in the past tense to match the time frame, so we use "were burnt." The subject of the sentence is "Guys" and they are the ones experiencing the action of being burnt on fire.

10. Guy Fawkes was known as Guido Fawkes.
Explanation: In this sentence, we are talking about the identity of Guy Fawkes. The verb "know" needs to be in the past tense to match the time frame, so we use "was known." The subject of the sentence is "Guy Fawkes" and he is the one being referred to as Guido Fawkes.