阅读下面材料,在空白处填入1个适当的单词或括号内单词的正确形式。
On May 18, it was announced that China 【小题1】 (achieve) success in drilling fire ice, a frozen mixture of water and natural gas, from the South China Sea. 【小题2】 (official) known as methane hydrates (甲烷水合物), fire ice produces a high amount of energy when it is burnt and its chemical reaction produces nothing but dioxide and water.
Fire ice, both clean and energy-intensive, 【小题3】 (consider) the fuel of the future. But, the Chinese team succeeded in 【小题4】 (extract) fire ice for nearly eight successive days, which is a big breakthrough. However, it is too early 【小题5】 (say) a new energy source has been found. The worlds total fire ice reserve is about 21,000 trillion cubic meters,【小题6】, if extracted, could meet the worlds energy need for 1,000 years. But the【小题7】 (success) test drilling of fire ice does not mean it can be extracted for 【小题8】 (industry) use. China has to solve many problems 【小题9】 it can use fire ice as a source of energy.
It’s thought that only by 2025 at 【小题10】 earliest might people be able to look at realistic commercial options.