英语翻译：这是因为没有让人长时间在水下呼吸的机器

This was because that there is not any machine which is able to let humans breathe underwater for a long time.

Because there isn't any machine which can be used to breath under the water for long time.

修改 It is because that there isn't any machine which can be used to breath under the water for long time.

this is because that there are no machines which allow people to stay under water for a long time~.

This is a long time because there is no people in the underwater breathing machine