International visitors can be divided into ().
A. international tourists and international travelers
B. international travelers and international excursionists
C. international transit travelers and international excursionists
D. international tourists and international excursionists
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An international tourist is a visitor who spend () in the destination country.
A. more than one night
B. not more than one night
C. at least one night
D. at least two nights
It was in () that the first package holiday built around air transport was organized by Vladimir Raitz.
A. 1862
B. 1872
C. 1950
D. 1970
人民警察认为决定和命令有错误的，( )。
A. 可以自行决定不执行
B. 经请示后才能执行
C. 可以按规定提出意见，但不中止或改变执行
D. 可以按规定复议，但不终止或改变执行
关于维生素A醋酸酯的说法，错误的是
A. 维生素A醋酸酯化学稳定性比维生素A好
B. 维生素A醋酸酯对紫外线稳定
C. 维生素A醋酸酯易被空气氧化
D. 维生素A醋酸酯对酸不稳定
E. 维生素A醋酸酯长期储存时，会发生异构化，使活性下降
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