填 see,因为 look 后面通常不接 if 从句。又如下面的句子通常也用 see,不用 look:
See if you can find a seat. 看看你能否找到一个座位。
See if you can back up a bit further. 看看你能否把车再倒一点。
See if you can change his mind about coming with us. 看看你能否改变他和我们一起来的决定。
I’ll see if I can try and persuade her to come. 我看看能不能说服她来。