1 a) I'm doing my homework, (ii) so I can't come to the party with you.
В главной части форма глагола Present Continuous указывает на то, что действие выполняется в момент речи - это причина, почему говорящий не может пойти на вечеринку.
b) I do my homework (i) on the bus most days.
Present Simple в главной части в сочетании с most days обозначает регулярно совершаемое действие.
2 a) I'm not enjoying this film - (i) can we watch the other DVD?
речь о конкретном фильме, который смотрят в момент речи.
b) I don't enjoy films - ( ii) I prefer reading.
Формы Present Simple в обеих частях используются для описания предпочтений (то есть характеризуют) говорящего.
3 a) I'm looking for (ii) Maria. Have you seen her?
Говорящий ищет Марию в момент речи.
b) I look for (i) new artists. It's an interesting job.
Форма Present Simple глагола look указывает на обычно совершаемое действие (человек говорит о своей работе)
4 a) I'm standing (ii) on the bridge. I can see you!...
Ситуация происходит в момент речи.
b) I stand (i) on the bridge every day and watch the boats.
Present Simple глагола stand + слова every day указывают на привычку/регулярное действие
5 a) The train is arriving (ii) in London now. See you in 5 minutes.
Конкретная ситуация, действие происходит в момент речи.
b) The train arrives (i) late sometimes.
Sometimes - маркер Present Simple.
6 a) Are you using (i) this pen? No? OK, I'll use it for a moment.
Вопрос про конкретную ручку в момент речи. => Present Continuous
b) Do you use (ii) a pen and paper or do you do everything on the computer?
Вопрос про обычно совершаемое действие.
John collects money. - Money is collected by John.
2. Anna opened the window. - The window was opened by Anna.
3. We have done our homework. - Our homework has been done by us.
4. I will ask a question. - A question will be asked by me.
5. He can cut out the picture. - The picture can be cut out by him.
6. The sheep ate a lot. - A lot was eaten by the sheep.
7. We do not clean our rooms. - Our rooms are not cleaned by us.
8. William will not repair the car. - The car will not be repaired by William.
9. Did Sue draw this circle? - Was this circle drawn by Sue?
10. Could you feed the dog? - Could the dog be fed by you?