Dolphins are known as marine (41) ______they breathe air, they are warm-blood, and they bear live young ones called (42) ______ The size of dolphin is very greatly. (43)______ smallest dolphins are just about 50 kg in weight and 1.2 meters in length (44) ______the largest one can weigh up to 8.200 kg and is 10 meters long. Dolphins are sociable creatures. They swim together in group known as (45) ______They show great ability in the water. Dolphins are interested (46) ______humans and often rescue people in the sea (47) ______are in danger. They are intelligent creatures and make sounds to (48)_____ with each other. Scientists have studied dolphins (49) _____many years and are now looking into the possibility of dolphins that are able to carry (50) _____ tasks under the sea. 41. A. fish B. creatures C. mammals D. life 42. A. babies B. calves C. young D. diets 43. A. A B. An C. The D. And 44. A. when B. as C. while D. since 45. A. currents B. flocks C. herds D. teams 46. A. in B. at C. on D. of 47. A. which B. whose C. when D. who 48. A. talk B. communicate C. contact D. connect 49. A. in B. since C. for D. during 50. A. out B. in C. of D. wit Giúp e nha