The poor boy couldn't work the problem out. He wasn't ____ clever.

—Why are you so late?—The driver couldn’t see clearly because of the fog．____, the road was too icy．

As soon as his teacher begins lecturing, he begins to doze off, not intentionally but _____.

Though some foreign scientists had a ______ opinion of his new invention, his fellow workers never thought ____ of it.

 When they knew there was a panda in the zoo, the children could ___ wait to see it.