give up指行为或努力受挫或别的原因而主动放弃,可用作及物动词,跟名词或v－ing作宾语；也可作不及物动词；
give in指不再坚持自己的行为或观点等,而按别人的要求去做,即屈服的意思一般作不及物动词
give up sth/doing放弃某事/做某事.如:David gave up his work/smoking yesterday.
give in (to sb)(向某人)屈服.如:Liu Hulan never gave in to the enemy