Now I am answering the colleague's questions(отвечаю на вопросы коллег)
I started doing it at 10 o'clock
I have been doing it for 50 minutes.
Понятна постановка времен
В первом Present Continuous так как речь идет о действии происходящем в настоящий момент времени Мы не знаем когда началось и когда закончится это действие
Во втором Past Simple так как действие имело место в но точное время протекания этого действия не определено
В третьем Present Perfect Continuous так как действие началось в и еще продолжется (знаем сколько времени но всё ещё нет результата)
Now I am answering the colleague's questions(отвечаю на вопросы коллег)
I started doing it at 10 o'clock
I have been doing it for 50 minutes.
Понятна постановка времен
В первом Present Continuous так как речь идет о действии происходящем в настоящий момент времени Мы не знаем когда началось и когда закончится это действие
Во втором Past Simple так как действие имело место в но точное время протекания этого действия не определено
В третьем Present Perfect Continuous так как действие началось в и еще продолжется (знаем сколько времени но всё ещё нет результата)
54. The children will be really hungry when they get home because they will be running around all afternoon without any food.
55. Why don't you come round at 9 o'clock? The children will have gone to bed at that time so it will be nice and peaceful.
56. I'm not going to speak to her until she apologises.
57. Martin asked me if I would help him with English.
58. We will have been driving over five hundred kilometres by the time we reach the border.
59. You will be sick if you eat more chocolate.
60. Look out! We are going to hit the car in front.
61. Don't phone too early because I will be putting the baby to bed.
62. By the time I qualify I will have been studying law for six years.
63. He was not quite sure when his parents would come home.
64. Bob didn't know if the time-table for the next week would be changed.
65. By the time you get back, all the food will have gone.
66. You will not be able to enter the building if you don't have your identity card.
67. The doctor told Carol that a week in the country would make her feel better.
68. When I learn a thousand English words, will I be able to read a newspaper?
69. We will return the reference material to the check-out-desk after we examine it.
70. Tom promised that he would phone us again at the weekend.
71. The film probably will not have finished until midnight.
72. We were anxious if the police would find the criminal.
73. Hopefully she will have dinner cooked for us by the time we get home.
74. I'm sure if we don't get there before seven they will have eaten and drunk everything.
75. I hope you will not forget your promise by tomorrow.
76. Will you see Nick tomorrow by any chance?
77. I'm sure you will have recovered by then from the shock of meeting Jason here.
78. I'll stay up late tonight to watch a film on television.
79. By Christmas I will have been working in this office for ten years.
80. A new video shop will be opened today. I will meet my friends there this afternoon.