Nà háizi yī liǎn dāizhì, duì zhōuwéi de shìwù háo wú fǎnyìng.
The child had a blank expression and showed no reaction to the surroundings.
Tips
usage
呆滞 can describe a person's expression or demeanor (blank, dull, vacant) or an economic/market condition (sluggish, stagnant). The dual usage makes it a versatile adjective in both literary and economic writing.