  While recent advancements in large language models (LLMs) bring us closer to
achieving artificial general intelligence, the question persists: Do LLMs truly
understand language, or do they merely mimic comprehension through pattern
recognition? This study seeks to explore this question through the lens of
syntax, a crucial component of sentence comprehension. Adopting a natural
language question-answering (Q&A) scheme, we craft questions targeting nine
syntactic knowledge points that are most closely related to sentence
comprehension. Experiments conducted on 24 LLMs suggest that most have a
limited grasp of syntactic knowledge, exhibiting notable discrepancies across
different syntactic knowledge points. In particular, questions involving
prepositional phrase attachment pose the greatest challenge, whereas those
concerning adjectival modifier and indirect object are relatively easier for
LLMs to handle. Furthermore, a case study on the training dynamics of the LLMs
reveals that the majority of syntactic knowledge is learned during the initial
stages of training, hinting that simply increasing the number of training
tokens may not be the `silver bullet' for improving the comprehension ability
of LLMs.
