He questioned my actions, suspecting that I was hiding something.

He was watching the movie without paying much attention.

He was doing other work while letting the movie play without watching it attentively.

He was captured by the enemy during the war and subjected to water torture.

I could see her undyed hair roots, which made me realize that she dyes her hair.

Heavy hydrogen is one of the isotopes of hydrogen.

She is interested in numerology.

He is majoring in applied mathematics at university.

Combinatorial mathematics is a branch of mathematics that studies the combinations of things.

The number subtracted from the minuend is called the subtrahend.