题目选项分析

The yield of natural gas from Norway's Troll gas field is expected to increase annually until the year 2005, then stabilizing at six billion cubic feet a day, which will allow such an extraction rate for at least 50 years' production.

The yield of natural gas from Norway's Troll gas field is expected to increase annually until the year 2005 and then to stabilize at six billion cubic feet a day, an extraction rate that will allow at least 50 years' production.