The United States of America is a union of fifty states and is the third largest country in the world

Compound vs. Complex Sentences

Only independent clauses joined by one of the above coordinating conjunctions can be considered a compound sentence.
If you ever see an independent clause joined by a dependent clause, you're looking at a complex sentence. For example:

• 
  When I visit my mother, I eat cookies.
  

This is not a compound sentence. "When I visit my mother" is a dependent clause (doesn't express a complete thought) and a coordinator is not used.

• 
  I like to fish because fishing is fun.
  

This is not a compound sentence. Although "I like to fish" is an independent clause and "fishing is fun" is an independent clause, "because" is not a coordinating conjunction. Therefore, "because fishing is fun" is a dependent clause (it doesn't express a complete thought).

Exercises.

Упражнение 1. Make up compound sentences by using the right coordinating conjunctions in brackets.

1. 
   His job is very hard, (yet / therefore) his salary is low.
   
2. 
   I’m sorry I opened your handbook, (however / but) I mistook it for mine.
   
3. 
   Alex lost his job a year ago, (however / or) he soon managed to find another one.
   
4. 
   I know she’s hard to deal with, (and / nevertheless) you ought not to be rude to her.
   
5. 
   I’ve been living here for many years, (but / and) I don’t know the place very well.
   
6. 
   Her life is very peaceful,l (or / yet) she is always complaining.
   
7. 
   We haven’t got much in common, (moreover / but) we get on with each other fairly well.
   
8. 
   Тоm is 17 (or / and) he is studying at college.
   
9. 
   The rent is reasonable, (moreover / but) the location is perfect.
   
10. 
    My mum dislikes pets, (nevertheless / and) she bought a puppy for us.
    
11. 
    You can take a horse to water (and / but) you can’t make him drink.
    
12. 
    She was rushing to the office, (therefore / but) she couldn’t talk to me.
    
13. 
    A lot of novels are published every year, (therefore / however) very few of them become bestsellers.
    
14. 
    I didn’t talk to the Director (or / but) I talked to the Manager.
    
15. 
    Sam sat down on the bench (but / and) Lucy sat besides him.
    

Упражнение 2. Make up complex sentences by using the right subordinating conjunction

1. 
   Since / Just as there’s too much work to do, we won’t go on holiday.
   
2. 
   I’d better take an umbrella in саse /whether it rains.
   
3. 
   Just keep an eye on the baby while / whereas I cook the supper, will you?
   
4. 
   Many of the children feel more confident if / though they work in groups.
   
5. 
   Although / in order that he hasn’t said anything, he seems to be upset about it.
   
6. 
   You must be careful while / unless you wash this delicate silk blouse.
   
7. 
   I’d like to find out when / even if the classes begin.
   
8. 
   By / as long as the time you receive this letter, I’ll have left for Japan.
   
9. 
   At last, after / as long as he had tried three times, he passed his exam.
   
10. 
    The manager didn’t offer him the job because / although his appearance was very untidy.
    
11. 
    Even if / When there are small children around, it’s better to put breakable ornaments out of their reach.
    
12. 
    Unless / Until you hurry, you won’t catch the bus.
    
13. 
    I couldn’t resist having another slice of cake in case / even though I was supposed to be losing some weight.
    
14. 
    Leave the cake in the oven until / because it turns brown.
    

Упражнение 3. Укажите правильный союз.

1. 
   Mark can’t leave his job ... he has found another one. (A as soon as / В until / C when)
   
2. 
   My son’s hair got darker ... he got older. (A as / В if / C as long as)
   
3. 
   I’ll lend you this book ... I have finished reading it. (A unless / В in case / C when)
   
4. 
   … I lived farther from the school than any other pupil, I was often the last to arrive. (A Although / В Despite /C Since)
   
5. 
   I stood on a chair ... I could reach the upper shelf. (A because / В so that /C as)