The following expressions on the construction of patent search formulas are correct ().
A. Recall rate and precision rate are commonly used to measure the effectiveness of patent searches
B. "Precision" usually uses a combination of partial elements to search
C .Recall rate is often used to measure the comprehensiveness of search results
D. Precision rate is often used to measure the accuracy of search results
E. The key to "retrieval" lies in everything Element combination search
Correct answer: ACD