these are brought  (a)   to the cities

they built the .................... ......................s too close to sea level, and now sea levels are rising, they’re more or less useless

(a)  

it’s qoing to be a long time before countries come to a decision on what principles they’re prepared to ............... .................

(a)  

We should mention some geographical factors, things like  (a)   s and river estuaries and coastal erosion and so on

We should mention some geographical factors, things like wetlands and river (a)    and coastal erosion and so on

scientists have been working out how we can (a)   energy from renewable sources, such as the sun and wind, without causing pollution.

Today I’ll outline marine renewable energy - also called ocean energy - which (a)   es the movement of the oceans.

Burning fossil fuels, like gas, coal and oil, seriously damages the environment and they’ll eventually ....................... ................

(a)  

scientists have been working out how we can derive energy from  (a)    sources

Marine renewable energy can be divided into three main categories: wave energy, (a)   energy and ocean thermal energy conversion

Marine renewable energy can be divided into three main categories: wave energy, tidal energy and ocean (a)   energy conversion

This adds to the difficulty of creating (a)   technology: ideally all the waves would travel smoothly and regularly along the same straight line.

the source is constant, and there’s no danger of waves coming to a  (a)  

Electricity can be (a)   d using onshore systems, using a reservoir, or offshore systems.

Electricity can be generated using onshore systems, using a  (a)   , or offshore systems.

But the problem with ocean waves is that they’re (a)   , with the wind making them travel in every direction.

Another drawback is that sand and other  (a)    on the ocean floor might be stopped from flowing normally, which can lead to environmental problems.

The (a)   will contain sixteen hydro turbines.

water rushes through the breakwater, activating the turbines, which turn a  to produce electricity.

(a)  

It pours powerfully out of the (a)   , driving the turbines in the breakwater in the opposite direction

there are fears that lagoons might harm both fish and birds, for example by disturbing migration patterns, and causing a build-up of (a)   , affecting local ecosystems.