天然气中成份以()为主,含量高达()%,其次是乙烷、丙烷、二氧化碳等。
参考答案:甲烷,95.9
—Why did he leave that position?
—He_____a better position. [ ]
A. offer
B. offered
C. am offered
D. was offered
需要在飞行放行单上填写或附加每个飞行机组成员飞行乘务员以及指定机长的名字的是()航空公司和营运人。