When my interest shifted from space to the sea,I never expected it would cause such confusion among my friends,yet I can understand their feelings.(1)_______________________.To explain, I'd like to share my reasons behind this unusual change of mind.The first excuse I give is an economic one.Underwater exploration is so much cheaper than space flight.The first roundtrip ticket to the moon is going to cost at least 10 billion dollars if you include research and development.By the end of this century, the cost will be down to a few million.On the other hand,the diving suit and a set of basic tools needed for skin-diving can be bought for 20 dollars.My second argument is more philosophical.(2)_______________________.If we wish to survive in either for any length of time,we need to have mechanical aids.(3)_____________________________.The feelings and the emotions of a man beneath the sea will be much like those of a man beyond the atmosphere.
