It was very difficult to make a heavy machine fly. But they were able to make it fly.

使很重的机器飞起来是很困难的，但是他们终于使它飞了起来。

youdao

It was very difficult to make a heavy machine fly. But they were able to make it fly.

使很重的机器飞起来是很困难的，但是他们终于使它飞了起来。

youdao