[译] 我看她并不明白你说的话。
[误] I suppose she didn’t understand what you said.

[正] I don’t suppose she understand what you said.
[注] suppose 后接的从句含否定之意，英语的习惯表达方式是，把否定词放在 suppose 之前，后接的从句中动词用肯定形式。