Suggest improvements for the highlighted problem area:
Liyao told Lu that she should explain how the Yangtze River can be both a lake and a dam. At Lake Poyanghu during the winter, the river comprises small streams on a broad lake bed. In the summer, high waters fill the reservoir and curb the inflow of tributaries like a dam.
Liyao also described how she tried to visit a friend which had called for help from the other side of the lake. It was summer and they always warn you about the high waters. While rowing across Lake Poyanghu, Liyao became exhausted and decided, with great regret, to return home. It was too far across.
- Pronoun Reference-
A later sentence in our opening paragraph shows another problem with pronoun reference:
It was summer and they always warn you about the high waters.
Here, the people being referred to have not yet been mentioned. Who are they? Who is this you? If these words are spoken in casual conversation, we usually understand what is meant. But for our writing to be clear, we should edit out these indefinite references by rewriting the sentence:
It was summer and it was well known that the lake level was high.