d
only+不定式表示意外结果；only+现在分词：表示意料中的结果：
如：
I hurried to the station,only to find the train had gone.
Sap passes right through the aphids' bodies,only getting a little thicker and sweeter .
汁液直接流过蚜虫的身体,结果只是变得更稠、更甜.