1．As is known to all, ______ great scientific achievements may have ______ positive effect on our life as well as society.
A．/; a B．the; a C．the; / D．/； /
2．What do you mean? I can’t _______ you and I can’t ______ your meaning.
A．understand; catch B．follow; grasp
C．follow; understand D．all the above
