50. How long have you had it?

51. If you don't leave your computer on when you don't use it, you will save electricity.

52. If we cut down trees in the forest, where will be more floods.

53. I like cartoons although I don't watch them much.

54. I haven't seen her since last Christmas day

`50.` How long have you had it?

`51.` If you leave your computer on when you don't use it, you won't save electricity.

`52.` If we don't cut down trees in the forest, where won't be more floods.

`53.` Although I don't watch cartoons much, I like them.

`54.` I haven't seen her since last Christmas day.