51. ___________________(necessary) is the mother of invention.

50.The mayor presented a silver cup to the_____________(win).

49.The microscope is a ________________(science) instrument.

48.The bad weather ___________________(encourage) people from attending the

parade.

47. He is no____________(strange) to poverty.

46. It's___________(sun) today , let's go fishing.

45.That is unacceptable in our_______________(social).

44.Tom is really a ______________(trouble) boy.

43.We had no _____________ (succeed) in finding a new flat.

42.I’m afraid it’s completely _________________(worth).