Definition: to be certain Level: A2
我知道她听到这个消息会非常高兴。
I ___know that she'll be really pleased to hear the news.
我不知道是否应该告诉她。
I don't ___know whether I should tell her or not.
我找不到信息，但我知道课是在星期二。
I can't find the information, but I ___know the class is on Tuesday.
