The forty years from the 1930s to the 1970s was an important period
A. in the development of air transportation
B. the earliest passenger flights were successfully operated
C. to make travel easy and pleasant for the passengers
D. to provide different services
E. the shortage of qualified pilots
F. traveling by air was very cheap
查看答案
社会保险基金主要来自于用人单位和职工缴纳的社会保险费，没有国家财政的投入。()
参考答案：错误
Air transport companies use different planes__________.
A. in the development of air transportation
B. the earliest passenger flights were successfully operated
C. to make travel easy and pleasant for the passengers
D. to provide different services
E. the shortage of qualified pilots
F. traveling by air was very cheap
Paragraph 5__________. 查看材料
Airport services
B. Training of pilots
C. Beginning period
D. Rapid growth in the U.S.
E. Development
F. Competition
The United States was the country where__________. 查看材料
A. in the development of air transportation
B. the earliest passenger flights were successfully operated
C. to make travel easy and pleasant for the passengers
D. to provide different services
E. the shortage of qualified pilots
F. traveling by air was very cheap
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