Generally, what is used to inflate life rafts?().
A、Non-toxic gas
B、oxygen
C、Hydrogen
D、Helium
A、Non-toxic gas
B、oxygen
C、Hydrogen
D、Helium
A、predicted in Tidal Current Tables B、unpredictable C、generally constant D、generally too weak to be of concern
A、the most common method used in the United States B、too expensive for common use C、generally safe to sea life D、generally harmful to sea life
A、1.Paragraph①() B、2.Paragraph②() C、3.Paragraph③() D、4.Paragraph④() E、5.Paragraph⑤() F、A. What is the function of audio courses? H、B. What is the function of flash cards? I、C. What is the function of traditional courses? J、D. What are the most useful tools for language learning? K、E. What is the function of computer-aided courses? F. What can help you a lot with your language learning? 下列选项正确的是()。