社会保障基金的投资必须首先考虑()原则
A.流动性
B.安全性
C.收益性
D.分散投资
参考答案:B
Jenny hopes that Mr. Smith will suggest a good way to have her written English ________.
A.improved
B.improving
C.to improve
D.improve
速度配平的条件是().
A.起飞离地20秒到A/P接通之前
B.起飞阶段结束
C.空速大于64节
D.A/P接通之后