It is polite to say “Thank you" and openIt is polite to say “Thank you" and open doors for people.老师说用动词不定式,为什么是动词不定式,动词不定式一定要两个动词吗?

It is polite to say＿(再见) to your friends when ...It is polite to say＿(再见) to your friends when you leave their home. it is polite to do It is _____to say to your mother like this Do it _____(polite) It is polite ___( speak) to the old ______( polite). It's polite to say please英语同义句 Is it polite to eat noisily? it is polite to follow them to say ''please '' is more polite同义句（）please' is more polite It is polite to say “Thank you and openIt is polite to say “Thank you and open doors for people.老师说用动词不定式,为什么是动词不定式,动词不定式一定要两个动词吗? I ___to leave without __goodbye.该选什么?a think it is not polite,sayb thinks it is not polite,sayingc don't think it is polite,say d don't think it is polite,saying I ___to leave without __goodbyea think it is not polite,sayb thinks it is not polite,sayingc don't think it is polite,say d don't think it is polite,saying it is safe to say It is not polite to stare at others. It is polite for/of you to do,哪个对? It is ________ polite to sayMay I come in ?before you come in.A.much B.more C.too D.a lot It's polite for students _____ hello to teachers?A.to say B.saying C.says D.say Be polite to your parents,don't you say it again后半句是什么用法? It's polite to say sorry when you knock into someone carelessly是什么意思