打开text-object帮助。

常用的几个命令，做下笔记：
    "dl"    delete character (alias: "x")        |dl|
    "diw"    delete inner word            *diw*
    "daw"    delete a word                *daw*
    "diW"    delete inner WORD (see |WORD|)        *diW*
    "daW"    delete a WORD (see |WORD|)        *daW*
    "dd"    delete one line                |dd|
    "dis"    delete inner sentence            *dis*
    "das"    delete a sentence            *das*
    "dib"    delete inner '(' ')' block        *dib*
    "dab"    delete a '(' ')' block            *dab*
    "dip"    delete inner paragraph            *dip*
    "dap"    delete a paragraph            *dap*
    "diB"    delete inner '{' '}' block        *diB*
    "daB"    delete a '{' '}' block            *daB*