Invention can be ________ as it may suddenly begin just by noticing something usual.
Don’t leave the water_______ while you brush your teeth.
The salesman scolded the girl caught ______ and let her off.
11. Though I have often heard this song ______, I have never heard you ______ it.
____________, they have been struggling against the snowstorm for ten hours.
Our teacher looked here and there on our playground ________ looking for something.