用英语说我不明白,是I can't understand 还是 I don't understand

问题描述:

用英语说我不明白,是I can't understand 还是 I don't understand
到底应该说是can't 还是don't
我不爱你 又怎么说呢?

是I don't understand.
问句是:Do you understand?
I don' love you.
I hate you.(我讨厌你)