Copernicus maintained that the earth_____round the sun.
A
表述永恒的真理或客观规律用一般现在时，不管主句谓语用什么时态。而“地球绕着太阳转”是客观规律，所以选a
Itwasnotuntilshehadfinishedallherwork_____.
_____alltherepresentativesstillnotthere，themeetingwaspostponedforseveralhours.
Children who are over-protected by their parents may become_____.