If we did not use alternative sources of energy more, we would destroy the planet.

A. Tourists are free to learn about the vital eco-systems before arriving.

B. It is optional for tourists to learn about the vital eco-systems before arriving.

C. Tourists are not required to learn about the vital eco-systems before arriving.

D. Tourists are required to learn about the vital eco-systems before arriving.

A. You will support local community if you stay in locally owned accommodation and buy products from local people.

B. You will support local community unless you stay in locally owned accommodation and buy products from local people.

C. You stay in locally owned accommodation and buy products from local people because you will support local community.

D. You stay in locally owned accommodation and buy products from local people only if you will support local community.

A. You should try to limit the use of natural resources unless they are running out in many tourist destinations.

B. Because you try to limit the use of natural resources, they are running out in many tourist destinations.

C. You should try to limit the use of natural resources, so they are running out in many tourist destinations.

D. Natural resources are running out in many tourist destinations, so you should try to limit their use.

A. Whenever you can travel by train instead of plane.

B. Traveling by train is much better than traveling by plane.

C. You can never avoid travelling, so take the train or the plane.

D. Instead of travelling by plane, you can travel by train.

A. Tourists provide us with the principles of ecotourism throughout their trip.

B. We aim at providing the principles of ecotourism for tourists throughout their trip.

C. We provide ourselves with the principles of ecotourism through our trip.

D. We need more information about the principles of ecotourism for our trip.

A. Eco-travellers are not required to protect the environment.

B. Eco-travellers are encouraged not to have any negative impacts on the environment.

C. It is eco-travellers' responsibility to prevent or minimize any negative impacts on the environment.

D. Eco-travellers have never had any negative impacts on the environment.

A. We don't allow the local people to hunt endangered species for our consumption, so they will become extinct sooner.

B. If we allowed the local people to hunt endangered species for our consumption, they would become extinct sooner.

C. We don't allow the local people to hunt endangered species for our consumption unless they will become extinct sooner.

D. They will become extinct sooner if we don't allow the local people to hunt endangered species for our consumption.