13.______studying abroad can be hard, it can broaden your understanding of the word.
The River Nile ___ flood large areas, but now the water of it ___ produce electricity.
We learned a lot from her father, an engineer ___ does research ___ science.
You should make a careful plan ___ the experiment.
Here’s my card, let’s keep in ___.
I don’t know the restaurant, but it’s __ to be quite a good one.