Нужно задать вопрос 1) Sally is using a ladder to collect rubbish.
2) Dave and Sally are planting flowers.
3) He has been planting flowers for two hours.
4) Dave has joined the Eco-helpers club.
5) Dave joined the Eco-helpers club.
6) Sally collects rubbish in the park every Saturday.
7) We don't help them.
8) They will have to leave the city.
9) That's not interesting.
10) I can join the Eco-helpers club.
11) We really need volunteers.
12) I'll join the Eco-helpers club.