题目内容：
They ________ extensive and possibly dangerous actual flight training. A. undertake B. undergo C. underplay D. underuse
参考答案：【答案仅供学习，请勿对照自行用药等】
选择题：They________extensiveandpossiblydangerousactualflighttraining.
- 题目分类：习题答案
- 题目类型：选择题
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