英语听力精选进阶版 14429（在线收听）

Children aid malaria vaccine hunt

Vocabulary

rife

something unpleasant which is common

resistant

not affected or harmed by an illness

parasite

living thing which lives inside other larger living things and uses them for food

bursting out

breaking open and leaving; escaping

injecting

putting liquid inside a body using a needle

trials

tests

assess

decide the importance (of something)