The sentence in the Present Perfect: A) It is now possible to make energy from human movement.
B) The process is environmentally friendly
C) These press against each other and generate power.
D) Large supplies of nappies are available.
E) Two architects have invented a plan called ‘The Crowd Farm’.

The equivalent of “be able to”:
A) have to
B) can
C) might
D) need
E) should

The sentence with Participle I:
A) Electricity or biofuel – a good alternative to oil because you can store it.
B) But growing plants especially for biofuel takes a lot of water, energy and land.
C) Using biomass is definitely going to be cheaper and more efficient in the future.
D) The nappies are heated up without oxygen.
E) One exciting possibility of biofuel production is from human waste – including dirty nappies.