如何将一列结构中的句子粘贴为一本“书”？

Question

假设我有一本书在数据框中表示，每个单元格都有不同的行。数据框将像这样创建：

data.frame(Bookname = c("This is sentence 1.", "This is sentence 2.",
                    "This is sentence 3.", "...", "This is sentence n."))

结果：

Bookname
"This is sentence 1."
"This is sentence 2."
"This is sentence 3."
...
"This is sentence n."

我如何将这本书做成一个整体？这样输出看起来像：

Bookname
"This is sentence 1. This is sentence 2. This is sentence 3. ... This is sentence n."