Rewrite the sentences in the passive voice (simple past) 1. Our parents bought the house.
2. My mother painted the doors.
3. The teacher gave him a present.
4. We did the exercises yesterday.
5. Paul sold his old motorbike.
6. He checked the car before going on a road trip.
7. My brother cleaned the carpets last week.​

1. The house was bought by my parents

2. the doors were painted by mother

3.  he got a present from his teacher

4 Yesterday we did exercises

5. The old motorbike was sold by Paul

6. Before goin on a road trip, he checked the car.

7. the carpets were cleaned last week by my brother.

Explanation:

a complex sentence consists of an independent clause and one or more dependent clauses.  

to write complex sentences, we must use subordinating conjunctions.  

all the complex sentences begin with a subordinating conjunction and when it occurs, a comma must be place at the end of the dependent clause. on the contrary, if the sentence begins with an independent clause, then no comma is used.

after  

although  

as  

because  

before  

if  

since  

when  

for example,  

after she won the competition, she became very popular.  

although my father was hurt, he continued fighting for his rights.  

as all of you got a ten, you will be able to leave early today.  

before he went to the war, he asked his parents to bless him.  

if it is cold, i won’t go out.  

since you didn’t bring the homework, you will get low grades.  

when it is hot in the town, everyone goes to the beach.  

i'm thinking it would be when compound subjects are joined by or, nor,either-or, neither-nor.