A: Sparks can't be replaced by fishing fire. These are two spaces. Spark is a distant view, and fishing fire is a close view of a river boat. Fishing fire is a single word, but for fishing boats, spark is a general word, which can be starlight, light and so on. .
Sorrow is homesickness at night. Fishing fire is a lamp on a fishing boat. In the poem of Nanjing Ferry, there is a river but no boat! !