问题：

What is the difference between conversion and suff

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答案：

Conversion is a word-formation process whereby a word of a certain word-class is shifted into a word of another word-class without the addition of an affix. For example, the verb attack (as in "The enemy attacked us at night." )corresponds to the noun attack (as in " The enemy launched an attack on us at night."). Suffixation is the formation of a new word by adding a suffix or a combining form to the base, and usually changing the word-class of the base. For example, the noun boy, by addition of the suffix -ish, is changed into the adjective boyish.