43.I usually read newspapers while I(wait) waiting for the bus.

44.The sky is very dark.I think it (rain) will rain 

45.I(not invite) .haven't invited  Recharch yet.

46.Before I (go).went..to live in spain,I (think) had thought it was the hot country.

47.We should go home.It(get) is getting darker and darker.

48.”I (try) have tried to get hold of you for ten minutes.Where have you been?”

49.My brother usually (go)goes to work early to avoid traffic jams.

50.I(not eat) haven't eatenanything for 2 days.

51 After his wife gave birth to thier first son,he imedately has bought a nice cradle.

43.waiting 

44 will rain 

45haven't invited  

46. had thought 

47. is getting 

48. have tried

49.goes 

50.haven't eaten 

51  has bought