It's this training flight for potential astronauts to experience near-zero gravity.

这是为潜在宇航员体验近零重力的训练飞行。

In fact, some people outside the base thought the Japanese planes must be new types of American aircraft on training flights. The sounds of guns and bombs soon showed how wrong they were.

事实上，基地外的一些人认为，日军飞机一定是美国训练飞行的新型飞机，而枪声和炸弹声很快就表明他们错了。