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UNIT 5 GRAMMAR

Conjunctions

Conjunctions are connecting words, such as and, or, and but. Conjunctions can be used to join words, phrases, and sentences. They also make compound subjects, compound predicates, and compound sentences.

Compound subject: and are . Compound predicate: The Magellan landed on Venus and took pictures. Compound sentence: Mars is a , but the is a . (Note the comma.) • Use and to join related ideas: is small and icy. • Use but to join different ideas: has rings, but the has craters. • Use or to suggest a choice: All the planets are very hot or very .

A Write the in each sentence.

1. is the largest planet, and it spins very fast. 2. Saturn’s rings are made of and icy rock. 3. There may have been life on Mars, but we are not sure. 4. One I will go to another planet or the moon. 5. Mars has two , but it does not have any rings. 6. Saturn and Jupiter are the largest planets in the . 7. Saturn is large, but Jupiter is larger. 8. A planet or other huge object may have knocked on its side. 9. Computers and help us study planets.

128 Grammar Space Probes to the Planets UNIT 5 GRAMMAR

B Use the conjunction and, or, or but to join each pair of sentences. Write the new sentences. Remember to add a comma.

1. Would you like to visit Mars? Would you rather go to Venus? 2. The moon is cold. Pluto is even colder. 3. Scientists think shrank after it formed. They are not sure. 4. Venus is not the closest planet to the sun. It is the hottest. 5. has strong . They push . 6. A landed on Mars. It took photos of rocks. 7. Four planets have rings. No planet has as many rings as Saturn. 8. Does Jupiter have the most moons? Does Saturn have more? 9. Space probes circled Mars, Venus, and Mercury. They are still circling. 10. Would you like to be an astronaut? Would you prefer being a scientist?

C Tell whether each sentence contains a compound subject or a compound predicate. Write CS for compound subject and CP for compound predicate.

11. Astronauts must study and exercise. 12. Zach and I went to the . 13. We saw a sky show and heard a lecture. 14. We learned about space shuttles and asked questions. 15. Venus and Mercury are closest to the sun. 16. Plants and animals could not live on Venus.

Grammar Space Probes to the Planets 129 UNIT 5 GRAMMAR

Review and Assess Write the correct conjunction in ( ) to complete each sentence.

1. Mars is called the Red Planet, (and, or) it is visible at night. 2. Mars is the fourth planet from the sun, (or, but) it is neither big nor small. 3. Scientists are not sure if there were plants (but, and) animals on Mars. 4. Is there on the surface of Mars, (but, or) is it dry? 5. The rocks on (but, and) Mars are much alike.

Write the letter of the word that completes each sentence.

6. Astronomers are scientists who study _____ planets. A of C and B but D if

7. _____ Edwin Hubble were famous astronomers. A and C but B since D maybe

8. The planets are far away, _____ they appear near through a . A or C but B and D not

9. You might see Venus, _____ only when the sky is clear. A or C and B but D for

10. Will there be a _____ a full moon? A but C and B so D or

130 Grammar Space Probes to the Planets