He works in a sports center ________ people in the use of the gym equipment. A: constructing B: destructing C: obstructing D: instructing

A car had been parked in the middle of the road, _____ the way and causing a traffic jam. A: obstructing B: moving C: objecting D: subjecting

中国大学MOOC: Vowels are sounds produced by constricting or obstructing the vocal tract at some place to divert, impede or completely shut off the flow of the air in the oral cavity.