I am not sure if she is from Canada. 还是I am not sure that she is from Canada.

Question

原题 is she from Canada? i'm not sure. 合并为一句

Answer 1

都可以，但表达意思略有不同。用if表示我不太确定她是不是来自加拿大，用that的话表示我不太确定她是来自加拿大的（对于她来自加拿大这件事情，我不确定，说不好）

Answer 2

I am not sure if she is from Canada. 或者 I am not sure whether she is from Canada or not.本回答被提问者和网友采纳

Answer 3

肯定是用if或者whether也行

Answer 4

I'm not sure if she is from Canada.

Answer 5

if.