他花了好几个小时深入研究这个课题。

He spent hours ___delving into the subject.

这位记者深入挖掘了这起政治丑闻背后的真相。

The journalist ___delved deep into the truth behind the political scandal.

她把手伸进包里，摸索着找手机。

She ___delved into her bag to find her phone.