1.This movie is by turn (= alternately) terrifying and very funny.
这电影一会儿令人毛骨悚然,一会儿滑稽可笑。
2.The dancers alternately arched and hunched their backs.
舞蹈者交替地将背向后起
3.The tempestite and non-tempestite occur alternately in vertical section.The development of tempestite is related to stratum, ancient landfom and water depth, tectonic location and clast supply.