Look! Somebody ______the blackboard．—Well, it wasn’t me．I didn’t do it

It will make ______big difference if this experimentbecomes ______ success.

下列各项中加点词的解释完全正确的一项是

People are very _____ about the problems ____ the environment.

Clearly, in a system _________ every decision is made on the basis of tradition alone, it may be difficult to achieve progress.