one of (sth); one out of a multitude; one (third, quarter, percent etc)[cedict]
必須
bì xūㄅㄧˋ ㄒㄩ
to have to; must[cedict]
回
huíㄏㄨㄟˊ
to circle; to go back; to turn around; to answer; to return; to revolve; Hui religious minority (Chinese Muslims); time; classifier for acts of a play; section or chapter (of a classic book)[cedict]