The problem is _____ we can master modern science and technology in a short time.
An ideal job should be one that ______ what you are good at with what you are interested in.
Which do you enjoy _____ the coming weekend, picnicking or a visit to Shanghai World Expo?
The child said that he had _____ the pen on the desk, but I thought he ____ to me.
Books of this kind ______ popular with the pre-school children.
--Are you satisfied with his reply? --Not at all. It couldn’t have been ______ .