I'm sure grandpa will be very happy ____(see) us

I'm sure grandpa will be very happy ____(see) us
I'm sure grandpa will be very happy ____(see) us

I'm sure grandpa will be very happy ____(see) us
填 to see
固定结构：be happy to do sth 做某事很开心
我确信爷爷看见我吗一定会很开心的.