48. What can be inferred from the text?

A. Successful language learners are cleverer.

B. Making mistakes is sometimes helpful.

C. successful language learners are dependent.

D. Successful learners are unwilling to make mistakes.

49. The writer wrote this text in order to _____.

A. encourage language learners to use these techniques

B. explain why language is difficult to learn

C. compare language learning with other types of learning

D. help language learners to communicate with others

50. What’s the passage mainly about?

A. Language learning

B. The skills of successful language learning

C. The importance of language learning

D. A successful language learner

C

In a mountainous area of Brazil, there is a kind of beautiful butterfly which can kill men. If people meet them, they will come down in great quantities to bite and kill, sucking blood and flesh through the wounds they cause.

In June, 1966, a boy named Marl Andre who went into the mountains in search of butterfly specimens (标本) was killed by these butterflies. A country boy saw him when he was just about to catch a butterfly. Suddenly thousands of butterflies came down upon him, covering him all over. The boy struggled and cried as he tried to free himself from their attack. Finally he fell senseless to the ground. Police examined his body and proved that he had died of bites by butterflies.

In New Guinea, there is a kind of needlefish which also kills men. Needlefish likes light. At night, it will swim near the lights of fishing boats, then suddenly shoot out of water like an arrow to its target, and force its 3-inch sharp mouth into a human body. Of-ten people are thrust in the eye, or through the chest or stomach, resulting in death. Sometimes it will even attack the people in a fishing boat in broad daylight.

About 10 persons in the world are killed by sharks every year, yet more than 240 people are killed by needlefish every year.

51. From the passage, we know that ______.

A. butterflies are living in the mountains

B. all butterflies like sucking blood and eating fish

C. the more beautiful a butterfly is, the more dangerous it is

D. the butterflies in a certain part of Brazil can kill men