保持

maintain neutrality

sustain a good relationship (with); maintain friendly relations (with)

be in agreement (with); conform with

maintain a steady rate of development

keep oneself clear-headed

hold the world record

maintain ecological balance; keep the balance of the ecosystem/nature

sustain nationwide stability and unity

remain modest and prudent

maintain trade relations

maintain contact (with); keep/stay in touch/contact (with); not to lose track of

keep/remain calm

keep back/stay away (from); hold off (from); keep a distance

maintain vigilance; keep being watchful

maintain one's health; keep fit

maintain a good momentum of growth of the national economy

maintain the old city's character; keep the ancient look of the city

keep the morale up

maintain stability and prosperity

keep up/maintain the dialogue (with)

maintain/preserve/keep one's independence

uphold the tradition; carry on/keep up the tradition

hold one's peace/tongue; stay silent; keep silence/silent

keep a safe distance from the car in front

keep quiet/still