In 2012, Jiaolong manned submersible made a 7000 meter sea trial. Before that, only the US, France and Russia had manned deep submarines in the world.
A.正确
B.错误
正确答案：B
In 2012, Jiaolong manned submersible made a 7000 meter sea trial. Before that, only the US, France and Russia had manned deep submarines in the world.
A.正确
B.错误
正确答案：B