To attempt grand tasks with insufficient knowledge or ability; to be overambitious relative to one's capabilities, often leading to failure.
他虽然很有热情，但经验不足，想一下子就负责整个项目，这恐怕有点知小谋大。
Although he is very enthusiastic, he lacks experience and wants to take charge of the entire project immediately; this might be a case of aspiring to great things with limited capability.
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