all trees or fruits in the prune family, such as the cherry and plum, as well as peach, apricot and apple trees, have a small amount of cyanide in the seeds that (a) are / is released when these seeds are chewed or digested. the human body normally detoxifies small amounts of this poison, but, if (b) eaten / eating in large amounts, it can cause some problems, like a rapid heartbeat, headache, and drowsiness. when serving apples, it is fun to cut the apple crossways, creating a circle with a star of seeds in the center. but be sure to help children remove the seeds and (c) throw away them / throw them away; do not let them eat the seeds.

형광펜 칠한 부분 질문 드립니다.
when serving apples파트를 어떻게 파악해야 하나요?
분사구문으로 생각하려고 하면, 주절의 주어(가주어 it)와 연결해서 말이 되야 하는데 그렇지 않은 것 같아서요.
해석은 그냥 사과를 제공할 때라고 되어 있는데, 주어가 없거나 주어, 동사가 모두 없거나 그런 것 같아서요.
어떻게 보고 해석하면 될까요?
답변 부탁드립니다.