be slow off the mark
US /bi sloʊ ɔf ðə mɑrk/
UK /bi sloʊ ɔf ðə mɑrk/

1.
反应迟钝, 理解慢
to be slow to understand, react, or do something
:
•
He tends to be slow off the mark when it comes to new technology.
他对新技术往往反应迟钝。
•
The company was slow off the mark in adapting to market changes.
该公司在适应市场变化方面反应迟钝。