A black hole exerts a strong gravitational pull and yet it has no matter .
A black hole exerts a strong gravitational pull and yet it has no matter .
一个黑洞能产生强大的吸力，但它却没有物质。
A black hole exerts a strong gravitational pull and yet it has no matter .
一个黑洞能产生强大的吸力，但它却没有物质。