中期
middle (of a period of time); medium-term (plan, forecast etc)
种脐
hilum; omphalodium (botany)
中企业
medium sized enterprise
中气层
mesosphere; upper atmosphere
中气层顶
mesopause; top of mesosphere
慎重其事
to treat a matter with due consideration (idiom)
物种起源
Charles Darwin's 'Origin of Species'
郑重其事
serious about the matter