He is as poor as a church mouse. Pick out the idiom in this sentence, then point out its structure, grammatical function and figure of speech.
For many weeks, I searched high and low to try to find some females to go with them, but without success. Pick out the idiom in this sentence, then point out its structure, grammatical functions and rhetorical feature.
属于病因性诊断的是
A. 心功能不全
B. 肺动脉高压
C. 呼吸衰竭
D. 病毒性心肌炎
E. 休克
Decide whether the following statement is true or false, based on your understanding of the stylistic features of idioms. Stylistically speaking, most idioms are neither formal nor informal.