41. As we all know, independence is very ________ for youngsters because sooner or later they will leave their families and live alone.A. essentialB. accurateC. flexibleD. temporary42. When dealing with students, teachers are supposed to adopt _________ and caring appro aches, as they are unique young individuals of different personalities.A. abstractB. efficientC. flexibleD. effective43. When the post fell ____, Dennis Bass was appointed to fill it.A. emptyB. blankC. vacantD. bare44. He's one of those people with a very ___ imagination -- every time he hears a noise he's convinced it's someone breaking in.A. adequateB. relevantC. abundantD. vivid45. After four years' research, we now have a ______ better understanding of the disease.A. veryB. farC. fairlyD. quite