Tā kànjiàn qián nányǒu zǒu jìnlái, lèngzhù le hǎojǐ miǎo.
Seeing her ex-boyfriend walk in, she froze for several seconds.
Tips
usage
愣 by itself = 'dazed/in a stupor'; the resultative 住 ('to hold/stick') makes it 'frozen in place by shock'. Compare 呆住 ('stupefied') which is similar but emphasizes blank-mindedness; 愣住 emphasizes the sudden mid-action freeze.
