如果表示简单的两个物体名词并列,则可以互换
例：he needs not only an apple but also a pear．
＝He needs both an apple and a pear．
但要表示动作的并列,则不可以,both and不表示动作的发生.
She doesn't only draw well but also sings nicely ．
这就换不了了.