What is needed at the beginning of sentence 1?

Daily communication is an essential part of our lives. nonetheless, breakdowns in communication are all too common. miscommunication cannot only be uncomfortable and embarrassing, but it can also be extremely harmful in certain situations. describe a situation of miscommunication you have experienced or witnessed. indicate the result and offer some ways the miscommunication could have been avoided. use the strategies mentioned in the lesson to you.

But we pulled at the grill [on the ground] and it gave way. and then we saw iron rings as steps leading down a shaft into a darkness without bottom. … it was a great tunnel. its walls were hard and smooth to the touch; it felt like stone, but it was not stone. on the ground there were long thin tracks of iron, but it was not iron; it felt smooth and cold as glass. we knelt, and we crawled forward, our hand groping along the iron line to see where it would lead. but there was an unbroken night ahead. what is the most likely explanation for the walls described in the bold text?

What is a ridge of rock near the water's edge